Everywhere: Remove unnecessary mutable attributes from lambdas

These lambdas were marked mutable as they captured a Ptr wrapper
class by value, which then only returned const-qualified references
to the value they point from the previous const pointer operators.

Nothing is actually mutating in the lambdas state here, and now
that the Ptr operators don't add extra const qualifiers these
can be removed.

30 files changed, 68 insertions, 68 deletions

diff --git a/Userland/Applications/MouseSettings/ThemeWidget.cpp b/Userland/Applications/MouseSettings/ThemeWidget.cpp
index 2c91c7e215..7c6c12661f 100644
--- a/Userland/Applications/MouseSettings/ThemeWidget.cpp
+++ b/Userland/Applications/MouseSettings/ThemeWidget.cpp
@@ -119,7 +119,7 @@ ThemeWidget::ThemeWidget()
     m_mouse_cursor_model->change_theme(theme_name);
 
     m_theme_name_box = find_descendant_of_type_named<GUI::ComboBox>("theme_name_box");
-    m_theme_name_box->on_change = [this](String const& value, GUI::ModelIndex const&) mutable {
+    m_theme_name_box->on_change = [this](String const& value, GUI::ModelIndex const&) {
         m_mouse_cursor_model->change_theme(value);
         set_modified(true);
     };
diff --git a/Userland/Applications/Terminal/main.cpp b/Userland/Applications/Terminal/main.cpp
index 4fbf80a25f..44db0407d5 100644
--- a/Userland/Applications/Terminal/main.cpp
+++ b/Userland/Applications/Terminal/main.cpp
@@ -199,18 +199,18 @@ static ErrorOr<NonnullRefPtr<GUI::Window>> create_find_window(VT::TerminalWidget
     find_forwards->set_fixed_width(25);
     find_forwards->set_icon(TRY(Gfx::Bitmap::try_load_from_file("/res/icons/16x16/downward-triangle.png"sv)));
 
-    find_textbox->on_return_pressed = [find_backwards]() mutable {
+    find_textbox->on_return_pressed = [find_backwards] {
         find_backwards->click();
     };
 
-    find_textbox->on_shift_return_pressed = [find_forwards]() mutable {
+    find_textbox->on_shift_return_pressed = [find_forwards] {
         find_forwards->click();
     };
 
     auto match_case = TRY(main_widget->try_add<GUI::CheckBox>("Case sensitive"));
     auto wrap_around = TRY(main_widget->try_add<GUI::CheckBox>("Wrap around"));
 
-    find_backwards->on_click = [&terminal, find_textbox, match_case, wrap_around](auto) mutable {
+    find_backwards->on_click = [&terminal, find_textbox, match_case, wrap_around](auto) {
         auto needle = find_textbox->text();
         if (needle.is_empty()) {
             return;
diff --git a/Userland/Libraries/LibCore/Promise.h b/Userland/Libraries/LibCore/Promise.h
index a419ef37fa..e38458fbd8 100644
--- a/Userland/Libraries/LibCore/Promise.h
+++ b/Userland/Libraries/LibCore/Promise.h
@@ -42,7 +42,7 @@ public:
     RefPtr<Promise<T>> map(T func(Result&))
     {
         RefPtr<Promise<T>> new_promise = Promise<T>::construct();
-        on_resolved = [new_promise, func](Result& result) mutable {
+        on_resolved = [new_promise, func](Result& result) {
             auto t = func(result);
             new_promise->resolve(move(t));
         };
diff --git a/Userland/Libraries/LibGUI/SettingsWindow.cpp b/Userland/Libraries/LibGUI/SettingsWindow.cpp
index 9affcec2e7..238f512101 100644
--- a/Userland/Libraries/LibGUI/SettingsWindow.cpp
+++ b/Userland/Libraries/LibGUI/SettingsWindow.cpp
@@ -47,7 +47,7 @@ ErrorOr<NonnullRefPtr<SettingsWindow>> SettingsWindow::create(String title, Show
 
     if (show_defaults_button == ShowDefaultsButton::Yes) {
         window->m_reset_button = TRY(button_container->try_add<GUI::DialogButton>("Defaults"));
-        window->m_reset_button->on_click = [window = window->make_weak_ptr<SettingsWindow>()](auto) mutable {
+        window->m_reset_button->on_click = [window = window->make_weak_ptr<SettingsWindow>()](auto) {
             window->reset_default_values();
         };
     }
@@ -55,24 +55,24 @@ ErrorOr<NonnullRefPtr<SettingsWindow>> SettingsWindow::create(String title, Show
     TRY(button_container->layout()->try_add_spacer());
 
     window->m_ok_button = TRY(button_container->try_add<GUI::DialogButton>("OK"));
-    window->m_ok_button->on_click = [window = window->make_weak_ptr<SettingsWindow>()](auto) mutable {
+    window->m_ok_button->on_click = [window = window->make_weak_ptr<SettingsWindow>()](auto) {
         window->apply_settings();
         GUI::Application::the()->quit();
     };
 
     window->m_cancel_button = TRY(button_container->try_add<GUI::DialogButton>("Cancel"));
-    window->m_cancel_button->on_click = [window = window->make_weak_ptr<SettingsWindow>()](auto) mutable {
+    window->m_cancel_button->on_click = [window = window->make_weak_ptr<SettingsWindow>()](auto) {
         window->cancel_settings();
         GUI::Application::the()->quit();
     };
 
     window->m_apply_button = TRY(button_container->try_add<GUI::DialogButton>("Apply"));
     window->m_apply_button->set_enabled(false);
-    window->m_apply_button->on_click = [window = window->make_weak_ptr<SettingsWindow>()](auto) mutable {
+    window->m_apply_button->on_click = [window = window->make_weak_ptr<SettingsWindow>()](auto) {
         window->apply_settings();
     };
 
-    window->on_close_request = [window = window->make_weak_ptr<SettingsWindow>()]() mutable -> Window::CloseRequestDecision {
+    window->on_close_request = [window = window->make_weak_ptr<SettingsWindow>()]() -> Window::CloseRequestDecision {
         if (!window->is_modified())
             return Window::CloseRequestDecision::Close;
 
diff --git a/Userland/Libraries/LibIDL/IDLParser.cpp b/Userland/Libraries/LibIDL/IDLParser.cpp
index f50b9427aa..48497b0e0e 100644
--- a/Userland/Libraries/LibIDL/IDLParser.cpp
+++ b/Userland/Libraries/LibIDL/IDLParser.cpp
@@ -114,7 +114,7 @@ HashMap<String, String> Parser::parse_extended_attributes()
         if (lexer.consume_specific('=')) {
             bool did_open_paren = false;
             auto value = lexer.consume_until(
-                [&did_open_paren](auto ch) mutable {
+                [&did_open_paren](auto ch) {
                     if (ch == '(') {
                         did_open_paren = true;
                         return false;
diff --git a/Userland/Libraries/LibIPC/Connection.cpp b/Userland/Libraries/LibIPC/Connection.cpp
index 465afd93de..fe69902221 100644
--- a/Userland/Libraries/LibIPC/Connection.cpp
+++ b/Userland/Libraries/LibIPC/Connection.cpp
@@ -172,7 +172,7 @@ ErrorOr<Vector<u8>> ConnectionBase::read_as_much_as_possible_from_socket_without
 
         auto bytes_read = maybe_bytes_read.release_value();
         if (bytes_read.is_empty()) {
-            m_deferred_invoker->schedule([strong_this = NonnullRefPtr(*this)]() mutable {
+            m_deferred_invoker->schedule([strong_this = NonnullRefPtr(*this)] {
                 strong_this->shutdown();
             });
             if (!bytes.is_empty())
@@ -211,7 +211,7 @@ ErrorOr<void> ConnectionBase::drain_messages_from_peer()
     }
 
     if (!m_unprocessed_messages.is_empty()) {
-        m_deferred_invoker->schedule([strong_this = NonnullRefPtr(*this)]() mutable {
+        m_deferred_invoker->schedule([strong_this = NonnullRefPtr(*this)] {
             strong_this->handle_messages();
         });
     }
diff --git a/Userland/Libraries/LibJS/Runtime/PromiseJobs.cpp b/Userland/Libraries/LibJS/Runtime/PromiseJobs.cpp
index 1eb425d476..5a29d2c43b 100644
--- a/Userland/Libraries/LibJS/Runtime/PromiseJobs.cpp
+++ b/Userland/Libraries/LibJS/Runtime/PromiseJobs.cpp
@@ -92,7 +92,7 @@ PromiseJob create_promise_reaction_job(VM& vm, PromiseReaction& reaction, Value
 {
     // 1. Let job be a new Job Abstract Closure with no parameters that captures reaction and argument and performs the following steps when called:
     //    See run_reaction_job for "the following steps".
-    auto job = [&vm, reaction = make_handle(&reaction), argument = make_handle(argument)]() mutable {
+    auto job = [&vm, reaction = make_handle(&reaction), argument = make_handle(argument)] {
         return run_reaction_job(vm, *reaction.cell(), argument.value());
     };
 
diff --git a/Userland/Libraries/LibWeb/Bindings/MainThreadVM.cpp b/Userland/Libraries/LibWeb/Bindings/MainThreadVM.cpp
index 01d155af7e..e5568fbc29 100644
--- a/Userland/Libraries/LibWeb/Bindings/MainThreadVM.cpp
+++ b/Userland/Libraries/LibWeb/Bindings/MainThreadVM.cpp
@@ -128,7 +128,7 @@ JS::VM& main_thread_vm()
 
                 // 5. Queue a global task on the DOM manipulation task source given global to fire an event named rejectionhandled at global, using PromiseRejectionEvent,
                 //    with the promise attribute initialized to promise, and the reason attribute initialized to the value of promise's [[PromiseResult]] internal slot.
-                HTML::queue_global_task(HTML::Task::Source::DOMManipulation, global, [&global, &promise]() mutable {
+                HTML::queue_global_task(HTML::Task::Source::DOMManipulation, global, [&global, &promise] {
                     // FIXME: This currently assumes that global is a WindowObject.
                     auto& window = verify_cast<HTML::Window>(global);
 
@@ -178,12 +178,12 @@ JS::VM& main_thread_vm()
         };
 
         // 8.1.5.4.2 HostEnqueueFinalizationRegistryCleanupJob(finalizationRegistry), https://html.spec.whatwg.org/multipage/webappapis.html#hostenqueuefinalizationregistrycleanupjob
-        vm->host_enqueue_finalization_registry_cleanup_job = [](JS::FinalizationRegistry& finalization_registry) mutable {
+        vm->host_enqueue_finalization_registry_cleanup_job = [](JS::FinalizationRegistry& finalization_registry) {
             // 1. Let global be finalizationRegistry.[[Realm]]'s global object.
             auto& global = finalization_registry.realm().global_object();
 
             // 2. Queue a global task on the JavaScript engine task source given global to perform the following steps:
-            HTML::queue_global_task(HTML::Task::Source::JavaScriptEngine, global, [&finalization_registry]() mutable {
+            HTML::queue_global_task(HTML::Task::Source::JavaScriptEngine, global, [&finalization_registry] {
                 // 1. Let entry be finalizationRegistry.[[CleanupCallback]].[[Callback]].[[Realm]]'s environment settings object.
                 auto& entry = host_defined_environment_settings_object(*finalization_registry.cleanup_callback().callback.cell()->realm());
 
@@ -224,7 +224,7 @@ JS::VM& main_thread_vm()
             auto* script = active_script();
 
             // NOTE: This keeps job_settings alive by keeping realm alive, which is holding onto job_settings.
-            HTML::queue_a_microtask(script ? script->settings_object().responsible_document().ptr() : nullptr, [job_settings, job = move(job), script_or_module = move(script_or_module)]() mutable {
+            HTML::queue_a_microtask(script ? script->settings_object().responsible_document().ptr() : nullptr, [job_settings, job = move(job), script_or_module = move(script_or_module)] {
                 // The dummy execution context has to be kept up here to keep it alive for the duration of the function.
                 Optional<JS::ExecutionContext> dummy_execution_context;
 
diff --git a/Userland/Libraries/LibWeb/DOM/AbortSignal.cpp b/Userland/Libraries/LibWeb/DOM/AbortSignal.cpp
index 4065ef10fa..c4199cf7fa 100644
--- a/Userland/Libraries/LibWeb/DOM/AbortSignal.cpp
+++ b/Userland/Libraries/LibWeb/DOM/AbortSignal.cpp
@@ -101,7 +101,7 @@ void AbortSignal::follow(JS::NonnullGCPtr<AbortSignal> parent_signal)
 
     // 3. Otherwise, add the following abort steps to parentSignal:
     // NOTE: `this` and `parent_signal` are protected by AbortSignal using JS::SafeFunction.
-    parent_signal->add_abort_algorithm([this, parent_signal]() mutable {
+    parent_signal->add_abort_algorithm([this, parent_signal] {
         // 1. Signal abort on followingSignal with parentSignal’s abort reason.
         signal_abort(parent_signal->reason());
     });
diff --git a/Userland/Libraries/LibWeb/DOM/Document.cpp b/Userland/Libraries/LibWeb/DOM/Document.cpp
index 38fb7e99b8..77cc5bf453 100644
--- a/Userland/Libraries/LibWeb/DOM/Document.cpp
+++ b/Userland/Libraries/LibWeb/DOM/Document.cpp
@@ -1559,13 +1559,13 @@ void Document::completely_finish_loading()
 
     // 4. If container is an iframe element, then queue an element task on the DOM manipulation task source given container to run the iframe load event steps given container.
     if (container && is<HTML::HTMLIFrameElement>(*container)) {
-        container->queue_an_element_task(HTML::Task::Source::DOMManipulation, [container]() mutable {
+        container->queue_an_element_task(HTML::Task::Source::DOMManipulation, [container] {
             run_iframe_load_event_steps(static_cast<HTML::HTMLIFrameElement&>(*container));
         });
     }
     // 5. Otherwise, if container is non-null, then queue an element task on the DOM manipulation task source given container to fire an event named load at container.
     else if (container) {
-        container->queue_an_element_task(HTML::Task::Source::DOMManipulation, [container]() mutable {
+        container->queue_an_element_task(HTML::Task::Source::DOMManipulation, [container] {
             container->dispatch_event(*DOM::Event::create(container->realm(), HTML::EventNames::load));
         });
     }
diff --git a/Userland/Libraries/LibWeb/DOM/EventTarget.cpp b/Userland/Libraries/LibWeb/DOM/EventTarget.cpp
index 8a90e5e7f4..5839f18e69 100644
--- a/Userland/Libraries/LibWeb/DOM/EventTarget.cpp
+++ b/Userland/Libraries/LibWeb/DOM/EventTarget.cpp
@@ -171,7 +171,7 @@ void EventTarget::add_an_event_listener(DOMEventListener& listener)
     // 5. If listener’s signal is not null, then add the following abort steps to it:
     if (listener.signal) {
         // NOTE: `this` and `listener` are protected by AbortSignal using JS::SafeFunction.
-        listener.signal->add_abort_algorithm([this, &listener]() mutable {
+        listener.signal->add_abort_algorithm([this, &listener] {
             // 1. Remove an event listener with eventTarget and listener.
             remove_an_event_listener(listener);
         });
diff --git a/Userland/Libraries/LibWeb/Fetch/FetchMethod.cpp b/Userland/Libraries/LibWeb/Fetch/FetchMethod.cpp
index 0c6b162c00..606643a9ac 100644
--- a/Userland/Libraries/LibWeb/Fetch/FetchMethod.cpp
+++ b/Userland/Libraries/LibWeb/Fetch/FetchMethod.cpp
@@ -125,7 +125,7 @@ JS::NonnullGCPtr<JS::Promise> fetch_impl(JS::VM& vm, RequestInfo const& input, R
             })));
 
     // 11. Add the following abort steps to requestObject’s signal:
-    request_object->signal()->add_abort_algorithm([&vm, locally_aborted, request, controller, promise_capability_handle = JS::make_handle(*promise_capability), request_object_handle = JS::make_handle(*request_object), response_object_handle]() mutable {
+    request_object->signal()->add_abort_algorithm([&vm, locally_aborted, request, controller, promise_capability_handle = JS::make_handle(*promise_capability), request_object_handle = JS::make_handle(*request_object), response_object_handle] {
         dbgln_if(WEB_FETCH_DEBUG, "Fetch: Request object signal's abort algorithm called");
 
         auto& promise_capability = *promise_capability_handle;
diff --git a/Userland/Libraries/LibWeb/Fetch/Fetching/Fetching.cpp b/Userland/Libraries/LibWeb/Fetch/Fetching/Fetching.cpp
index 127e27c195..4276238b47 100644
--- a/Userland/Libraries/LibWeb/Fetch/Fetching/Fetching.cpp
+++ b/Userland/Libraries/LibWeb/Fetch/Fetching/Fetching.cpp
@@ -260,7 +260,7 @@ WebIDL::ExceptionOr<Optional<JS::NonnullGCPtr<PendingResponse>>> main_fetch(JS::
         request->current_url().set_scheme("https"sv);
     }
 
-    JS::SafeFunction<WebIDL::ExceptionOr<JS::NonnullGCPtr<PendingResponse>>()> get_response = [&realm, &vm, &fetch_params, request]() mutable -> WebIDL::ExceptionOr<JS::NonnullGCPtr<PendingResponse>> {
+    JS::SafeFunction<WebIDL::ExceptionOr<JS::NonnullGCPtr<PendingResponse>>()> get_response = [&realm, &vm, &fetch_params, request]() -> WebIDL::ExceptionOr<JS::NonnullGCPtr<PendingResponse>> {
         dbgln_if(WEB_FETCH_DEBUG, "Fetch: Running 'main fetch' get_response() function");
 
         // -> fetchParams’s preloaded response candidate is not null
@@ -333,7 +333,7 @@ WebIDL::ExceptionOr<Optional<JS::NonnullGCPtr<PendingResponse>>> main_fetch(JS::
 
             // 2. Let corsWithPreflightResponse be the result of running HTTP fetch given fetchParams and true.
             auto cors_with_preflight_response = TRY(http_fetch(realm, fetch_params, MakeCORSPreflight::Yes));
-            cors_with_preflight_response->when_loaded([returned_pending_response](JS::NonnullGCPtr<Infrastructure::Response> cors_with_preflight_response) mutable {
+            cors_with_preflight_response->when_loaded([returned_pending_response](JS::NonnullGCPtr<Infrastructure::Response> cors_with_preflight_response) {
                 dbgln_if(WEB_FETCH_DEBUG, "Fetch: Running 'main fetch' cors_with_preflight_response load callback");
                 // 3. If corsWithPreflightResponse is a network error, then clear cache entries using request.
                 if (cors_with_preflight_response->is_network_error()) {
@@ -368,7 +368,7 @@ WebIDL::ExceptionOr<Optional<JS::NonnullGCPtr<PendingResponse>>> main_fetch(JS::
     }
 
     // 10. If recursive is false, then run the remaining steps in parallel.
-    Platform::EventLoopPlugin::the().deferred_invoke([&realm, &vm, &fetch_params, request, response, get_response = move(get_response)]() mutable {
+    Platform::EventLoopPlugin::the().deferred_invoke([&realm, &vm, &fetch_params, request, response, get_response = move(get_response)] {
         // 11. If response is null, then set response to the result of running the steps corresponding to the first
         //     matching statement:
         auto pending_response = PendingResponse::create(vm, request, Infrastructure::Response::create(vm));
@@ -898,7 +898,7 @@ WebIDL::ExceptionOr<JS::NonnullGCPtr<PendingResponse>> http_fetch(JS::Realm& rea
                 // HTTP-redirect fetch given fetchParams and response.
                 response = Infrastructure::OpaqueRedirectFilteredResponse::create(vm, *actual_response);
                 if (request->mode() == Infrastructure::Request::Mode::Navigate) {
-                    fetch_params.controller()->set_next_manual_redirect_steps([&realm, &fetch_params, response]() mutable {
+                    fetch_params.controller()->set_next_manual_redirect_steps([&realm, &fetch_params, response] {
                         (void)http_redirect_fetch(realm, fetch_params, *response);
                     });
                 }
@@ -914,7 +914,7 @@ WebIDL::ExceptionOr<JS::NonnullGCPtr<PendingResponse>> http_fetch(JS::Realm& rea
         }
 
         if (inner_pending_response) {
-            inner_pending_response->when_loaded([returned_pending_response](JS::NonnullGCPtr<Infrastructure::Response> response) mutable {
+            inner_pending_response->when_loaded([returned_pending_response](JS::NonnullGCPtr<Infrastructure::Response> response) {
                 dbgln_if(WEB_FETCH_DEBUG, "Fetch: Running 'HTTP fetch' inner_pending_response load callback");
                 returned_pending_response->resolve(response);
             });
@@ -1465,7 +1465,7 @@ WebIDL::ExceptionOr<JS::NonnullGCPtr<PendingResponse>> http_network_or_cache_fet
             inner_pending_response = TRY_OR_IGNORE(http_network_or_cache_fetch(realm, fetch_params, IsAuthenticationFetch::Yes));
         }
 
-        inner_pending_response->when_loaded([&realm, &vm, &fetch_params, request, returned_pending_response, is_authentication_fetch, is_new_connection_fetch](JS::NonnullGCPtr<Infrastructure::Response> response) mutable {
+        inner_pending_response->when_loaded([&realm, &vm, &fetch_params, request, returned_pending_response, is_authentication_fetch, is_new_connection_fetch](JS::NonnullGCPtr<Infrastructure::Response> response) {
             dbgln_if(WEB_FETCH_DEBUG, "Fetch: Running 'HTTP network-or-cache fetch' inner_pending_response load callback");
             // 15. If response’s status is 407, then:
             if (response->status() == 407) {
@@ -1515,7 +1515,7 @@ WebIDL::ExceptionOr<JS::NonnullGCPtr<PendingResponse>> http_network_or_cache_fet
                 inner_pending_response = TRY_OR_IGNORE(http_network_or_cache_fetch(realm, fetch_params, is_authentication_fetch, IsNewConnectionFetch::Yes));
             }
 
-            inner_pending_response->when_loaded([returned_pending_response, is_authentication_fetch](JS::NonnullGCPtr<Infrastructure::Response> response) mutable {
+            inner_pending_response->when_loaded([returned_pending_response, is_authentication_fetch](JS::NonnullGCPtr<Infrastructure::Response> response) {
                 // 17. If isAuthenticationFetch is true, then create an authentication entry for request and the given
                 //     realm.
                 if (is_authentication_fetch == IsAuthenticationFetch::Yes) {
@@ -1595,7 +1595,7 @@ WebIDL::ExceptionOr<JS::NonnullGCPtr<PendingResponse>> nonstandard_resource_load
 
     ResourceLoader::the().load(
         load_request,
-        [&realm, &vm, request, pending_response](auto data, auto& response_headers, auto status_code) mutable {
+        [&realm, &vm, request, pending_response](auto data, auto& response_headers, auto status_code) {
             dbgln_if(WEB_FETCH_DEBUG, "Fetch: ResourceLoader load for '{}' complete", request->url());
             if constexpr (WEB_FETCH_DEBUG)
                 log_response(status_code, response_headers, data);
@@ -1610,7 +1610,7 @@ WebIDL::ExceptionOr<JS::NonnullGCPtr<PendingResponse>> nonstandard_resource_load
             // FIXME: Set response status message
             pending_response->resolve(response);
         },
-        [&vm, request, pending_response](auto& error, auto status_code) mutable {
+        [&vm, request, pending_response](auto& error, auto status_code) {
             dbgln_if(WEB_FETCH_DEBUG, "Fetch: ResourceLoader load for '{}' failed: {} (status {})", request->url(), error, status_code.value_or(0));
             auto response = Infrastructure::Response::create(vm);
             // FIXME: This is ugly, ResourceLoader should tell us.
diff --git a/Userland/Libraries/LibWeb/Fetch/Fetching/PendingResponse.cpp b/Userland/Libraries/LibWeb/Fetch/Fetching/PendingResponse.cpp
index 7a4270475c..37dc4a180e 100644
--- a/Userland/Libraries/LibWeb/Fetch/Fetching/PendingResponse.cpp
+++ b/Userland/Libraries/LibWeb/Fetch/Fetching/PendingResponse.cpp
@@ -56,7 +56,7 @@ void PendingResponse::run_callback() const
 {
     VERIFY(m_callback);
     VERIFY(m_response);
-    Platform::EventLoopPlugin::the().deferred_invoke([strong_this = JS::make_handle(const_cast<PendingResponse&>(*this))]() mutable {
+    Platform::EventLoopPlugin::the().deferred_invoke([strong_this = JS::make_handle(const_cast<PendingResponse&>(*this))] {
         strong_this->m_callback(*strong_this->m_response);
         strong_this->m_request->remove_pending_response({}, *strong_this.ptr());
     });
diff --git a/Userland/Libraries/LibWeb/HTML/BrowsingContext.cpp b/Userland/Libraries/LibWeb/HTML/BrowsingContext.cpp
index d2e9306306..606b7d9bea 100644
--- a/Userland/Libraries/LibWeb/HTML/BrowsingContext.cpp
+++ b/Userland/Libraries/LibWeb/HTML/BrowsingContext.cpp
@@ -1142,7 +1142,7 @@ WebIDL::ExceptionOr<void> BrowsingContext::traverse_the_history(size_t entry_ind
     if (new_document->ready_state() == "complete"sv) {
         // then queue a global task on the DOM manipulation task source given newDocument's relevant global object to run the following steps:
 
-        queue_global_task(Task::Source::DOMManipulation, relevant_global_object(*new_document), [new_document]() mutable {
+        queue_global_task(Task::Source::DOMManipulation, relevant_global_object(*new_document), [new_document] {
             // 1. If newDocument's page showing flag is true, then abort these steps.
             if (new_document->page_showing())
                 return;
@@ -1211,7 +1211,7 @@ WebIDL::ExceptionOr<void> BrowsingContext::traverse_the_history(size_t entry_ind
     // 20. If hashChanged is true,
     if (hash_changed) {
         // then queue a global task on the DOM manipulation task source given newDocument's relevant global object
-        queue_global_task(Task::Source::DOMManipulation, relevant_global_object(*new_document), [new_document]() mutable {
+        queue_global_task(Task::Source::DOMManipulation, relevant_global_object(*new_document), [new_document] {
             // to fire an event named hashchange at newDocument's relevant global object,
             // using HashChangeEvent, with the oldURL attribute initialized to oldURL
             // and the newURL attribute initialized to newURL.
@@ -1330,7 +1330,7 @@ void BrowsingContext::set_system_visibility_state(VisibilityState visibility_sta
     // has changed to newState, it must queue a task on the user interaction task source to update
     // the visibility state of all the Document objects in the top-level browsing context's document family with newState.
     auto document_family = top_level_browsing_context().document_family();
-    queue_global_task(Task::Source::UserInteraction, Bindings::main_thread_vm().current_realm()->global_object(), [visibility_state, document_family = move(document_family)]() mutable {
+    queue_global_task(Task::Source::UserInteraction, Bindings::main_thread_vm().current_realm()->global_object(), [visibility_state, document_family = move(document_family)] {
         for (auto& document : document_family) {
             document->update_the_visibility_state(visibility_state);
         }
diff --git a/Userland/Libraries/LibWeb/HTML/FormAssociatedElement.cpp b/Userland/Libraries/LibWeb/HTML/FormAssociatedElement.cpp
index b983612c9f..9fe3b371ac 100644
--- a/Userland/Libraries/LibWeb/HTML/FormAssociatedElement.cpp
+++ b/Userland/Libraries/LibWeb/HTML/FormAssociatedElement.cpp
@@ -103,7 +103,7 @@ void FormAssociatedElement::reset_form_owner()
     if (is_listed() && html_element.has_attribute(HTML::AttributeNames::form) && html_element.is_connected()) {
         // 1. If the first element in element's tree, in tree order, to have an ID that is identical to element's form content attribute's value, is a form element, then associate the element with that form element.
         auto form_value = html_element.attribute(HTML::AttributeNames::form);
-        html_element.root().for_each_in_inclusive_subtree_of_type<HTMLFormElement>([this, &form_value](HTMLFormElement& form_element) mutable {
+        html_element.root().for_each_in_inclusive_subtree_of_type<HTMLFormElement>([this, &form_value](HTMLFormElement& form_element) {
             if (form_element.attribute(HTML::AttributeNames::id) == form_value) {
                 set_form(&form_element);
                 return IterationDecision::Break;
diff --git a/Userland/Libraries/LibWeb/HTML/HTMLHyperlinkElementUtils.cpp b/Userland/Libraries/LibWeb/HTML/HTMLHyperlinkElementUtils.cpp
index a1b4dcce09..b202a1abba 100644
--- a/Userland/Libraries/LibWeb/HTML/HTMLHyperlinkElementUtils.cpp
+++ b/Userland/Libraries/LibWeb/HTML/HTMLHyperlinkElementUtils.cpp
@@ -534,7 +534,7 @@ void HTMLHyperlinkElementUtils::follow_the_hyperlink(Optional<String> hyperlink_
     // set to source.
     // FIXME: "navigate" means implementing the navigation algorithm here:
     //        https://html.spec.whatwg.org/multipage/browsing-the-web.html#navigate
-    hyperlink_element_utils_queue_an_element_task(Task::Source::DOMManipulation, [url_string, target]() mutable {
+    hyperlink_element_utils_queue_an_element_task(Task::Source::DOMManipulation, [url_string, target] {
         target->loader().load(url_string, FrameLoader::Type::Navigation);
     });
 }
diff --git a/Userland/Libraries/LibWeb/HTML/HTMLInputElement.cpp b/Userland/Libraries/LibWeb/HTML/HTMLInputElement.cpp
index 952d6450e9..a719379e30 100644
--- a/Userland/Libraries/LibWeb/HTML/HTMLInputElement.cpp
+++ b/Userland/Libraries/LibWeb/HTML/HTMLInputElement.cpp
@@ -123,7 +123,7 @@ void HTMLInputElement::set_files(JS::GCPtr<FileAPI::FileList> files)
 void HTMLInputElement::update_the_file_selection(JS::NonnullGCPtr<FileAPI::FileList> files)
 {
     // 1. Queue an element task on the user interaction task source given element and the following steps:
-    queue_an_element_task(Task::Source::UserInteraction, [this, files]() mutable {
+    queue_an_element_task(Task::Source::UserInteraction, [this, files] {
         // 1. Update element's selected files so that it represents the user's selection.
         this->set_files(files.ptr());
 
diff --git a/Userland/Libraries/LibWeb/HTML/MessagePort.cpp b/Userland/Libraries/LibWeb/HTML/MessagePort.cpp
index c3d5dc1c7f..b65a366583 100644
--- a/Userland/Libraries/LibWeb/HTML/MessagePort.cpp
+++ b/Userland/Libraries/LibWeb/HTML/MessagePort.cpp
@@ -88,7 +88,7 @@ void MessagePort::post_message(JS::Value message)
 
     // FIXME: This is an ad-hoc hack implementation instead, since we don't currently
     //        have serialization and deserialization of messages.
-    main_thread_event_loop().task_queue().add(HTML::Task::create(HTML::Task::Source::PostedMessage, nullptr, [target_port, message]() mutable {
+    main_thread_event_loop().task_queue().add(HTML::Task::create(HTML::Task::Source::PostedMessage, nullptr, [target_port, message] {
         MessageEventInit event_init {};
         event_init.data = message;
         event_init.origin = "<origin>";
diff --git a/Userland/Libraries/LibWeb/HTML/Parser/HTMLParser.cpp b/Userland/Libraries/LibWeb/HTML/Parser/HTMLParser.cpp
index dbd8601ec2..62e042e8cc 100644
--- a/Userland/Libraries/LibWeb/HTML/Parser/HTMLParser.cpp
+++ b/Userland/Libraries/LibWeb/HTML/Parser/HTMLParser.cpp
@@ -250,7 +250,7 @@ void HTMLParser::the_end()
     }
 
     // 6. Queue a global task on the DOM manipulation task source given the Document's relevant global object to run the following substeps:
-    old_queue_global_task_with_document(HTML::Task::Source::DOMManipulation, *m_document, [document = m_document]() mutable {
+    old_queue_global_task_with_document(HTML::Task::Source::DOMManipulation, *m_document, [document = m_document] {
         // 1. Set the Document's load timing info's DOM content loaded event start time to the current high resolution time given the Document's relevant global object.
         document->load_timing_info().dom_content_loaded_event_start_time = HighResolutionTime::unsafe_shared_current_time();
 
@@ -279,7 +279,7 @@ void HTMLParser::the_end()
     });
 
     // 9. Queue a global task on the DOM manipulation task source given the Document's relevant global object to run the following steps:
-    old_queue_global_task_with_document(HTML::Task::Source::DOMManipulation, *m_document, [document = m_document]() mutable {
+    old_queue_global_task_with_document(HTML::Task::Source::DOMManipulation, *m_document, [document = m_document] {
         // 1. Update the current document readiness to "complete".
         document->update_readiness(HTML::DocumentReadyState::Complete);
 
diff --git a/Userland/Libraries/LibWeb/HTML/Scripting/Environments.cpp b/Userland/Libraries/LibWeb/HTML/Scripting/Environments.cpp
index 1b376b8e57..653a38ec95 100644
--- a/Userland/Libraries/LibWeb/HTML/Scripting/Environments.cpp
+++ b/Userland/Libraries/LibWeb/HTML/Scripting/Environments.cpp
@@ -228,7 +228,7 @@ void EnvironmentSettingsObject::notify_about_rejected_promises(Badge<EventLoop>)
     auto& global = global_object();
 
     // 5. Queue a global task on the DOM manipulation task source given global to run the following substep:
-    queue_global_task(Task::Source::DOMManipulation, global, [this, &global, list = move(list)]() mutable {
+    queue_global_task(Task::Source::DOMManipulation, global, [this, &global, list = move(list)] {
         // 1. For each promise p in list:
         for (auto promise : list) {
 
diff --git a/Userland/Libraries/LibWeb/HTML/Window.cpp b/Userland/Libraries/LibWeb/HTML/Window.cpp
index 4890025fa4..e3974b26a8 100644
--- a/Userland/Libraries/LibWeb/HTML/Window.cpp
+++ b/Userland/Libraries/LibWeb/HTML/Window.cpp
@@ -495,7 +495,7 @@ i32 Window::run_timer_initialization_steps(TimerHandler handler, i32 timeout, JS
     // 8. Assert: initiating script is not null, since this algorithm is always called from some script.
 
     // 9. Let task be a task that runs the following substeps:
-    JS::SafeFunction<void()> task = [this, handler = move(handler), timeout, arguments = move(arguments), repeat, id]() mutable {
+    JS::SafeFunction<void()> task = [this, handler = move(handler), timeout, arguments = move(arguments), repeat, id] {
         // 1. If id does not exist in global's map of active timers, then abort these steps.
         if (!m_timers.contains(id))
             return;
@@ -564,7 +564,7 @@ i32 Window::run_timer_initialization_steps(TimerHandler handler, i32 timeout, JS
 // https://html.spec.whatwg.org/multipage/imagebitmap-and-animations.html#run-the-animation-frame-callbacks
 i32 Window::request_animation_frame_impl(WebIDL::CallbackType& js_callback)
 {
-    return m_animation_frame_callback_driver.add([this, js_callback = JS::make_handle(js_callback)](auto) mutable {
+    return m_animation_frame_callback_driver.add([this, js_callback = JS::make_handle(js_callback)](auto) {
         // 3. Invoke callback, passing now as the only argument,
         auto result = WebIDL::invoke_callback(*js_callback, {}, JS::Value(performance().now()));
 
@@ -802,7 +802,7 @@ void Window::fire_a_page_transition_event(FlyString const& event_name, bool pers
 void Window::queue_microtask_impl(WebIDL::CallbackType& callback)
 {
     // The queueMicrotask(callback) method must queue a microtask to invoke callback,
-    HTML::queue_a_microtask(&associated_document(), [this, &callback]() mutable {
+    HTML::queue_a_microtask(&associated_document(), [this, &callback] {
         auto result = WebIDL::invoke_callback(callback, {});
         // and if callback throws an exception, report the exception.
         if (result.is_error())
@@ -906,7 +906,7 @@ WebIDL::ExceptionOr<void> Window::post_message_impl(JS::Value message, String co
 {
     // FIXME: This is an ad-hoc hack implementation instead, since we don't currently
     //        have serialization and deserialization of messages.
-    HTML::queue_global_task(HTML::Task::Source::PostedMessage, *this, [this, message]() mutable {
+    HTML::queue_global_task(HTML::Task::Source::PostedMessage, *this, [this, message] {
         HTML::MessageEventInit event_init {};
         event_init.data = message;
         event_init.origin = "<origin>";
@@ -961,7 +961,7 @@ void Window::start_an_idle_period()
 
     // 5. Queue a task on the queue associated with the idle-task task source,
     //    which performs the steps defined in the invoke idle callbacks algorithm with window and getDeadline as parameters.
-    HTML::queue_global_task(HTML::Task::Source::IdleTask, *this, [this]() mutable {
+    HTML::queue_global_task(HTML::Task::Source::IdleTask, *this, [this] {
         invoke_idle_callbacks();
     });
 }
@@ -985,7 +985,7 @@ void Window::invoke_idle_callbacks()
             HTML::report_exception(result, realm());
         // 4. If window's list of runnable idle callbacks is not empty, queue a task which performs the steps
         //    in the invoke idle callbacks algorithm with getDeadline and window as a parameters and return from this algorithm
-        HTML::queue_global_task(HTML::Task::Source::IdleTask, *this, [this]() mutable {
+        HTML::queue_global_task(HTML::Task::Source::IdleTask, *this, [this] {
             invoke_idle_callbacks();
         });
     }
diff --git a/Userland/Libraries/LibWeb/HTML/Worker.cpp b/Userland/Libraries/LibWeb/HTML/Worker.cpp
index ea796a3e0f..a3e717ecc1 100644
--- a/Userland/Libraries/LibWeb/HTML/Worker.cpp
+++ b/Userland/Libraries/LibWeb/HTML/Worker.cpp
@@ -154,7 +154,7 @@ void Worker::run_a_worker(AK::URL& url, EnvironmentSettingsObject& outside_setti
 
             auto& event_loop = get_vm_event_loop(m_document->realm().vm());
 
-            event_loop.task_queue().add(HTML::Task::create(HTML::Task::Source::PostedMessage, nullptr, [this, message]() mutable {
+            event_loop.task_queue().add(HTML::Task::create(HTML::Task::Source::PostedMessage, nullptr, [this, message] {
                 MessageEventInit event_init {};
                 event_init.data = message;
                 event_init.origin = "<origin>";
diff --git a/Userland/Libraries/LibWeb/Loader/Resource.cpp b/Userland/Libraries/LibWeb/Loader/Resource.cpp
index cc28cfae05..5832999c24 100644
--- a/Userland/Libraries/LibWeb/Loader/Resource.cpp
+++ b/Userland/Libraries/LibWeb/Loader/Resource.cpp
@@ -168,7 +168,7 @@ void ResourceClient::set_resource(Resource* resource)
         // This ensures that these callbacks always happen in a consistent way, instead of being invoked
         // synchronously in some cases, and asynchronously in others.
         if (resource->is_loaded() || resource->is_failed()) {
-            Platform::EventLoopPlugin::the().deferred_invoke([weak_this = make_weak_ptr(), strong_resource = NonnullRefPtr { *m_resource }]() mutable {
+            Platform::EventLoopPlugin::the().deferred_invoke([weak_this = make_weak_ptr(), strong_resource = NonnullRefPtr { *m_resource }] {
                 if (!weak_this)
                     return;
 
diff --git a/Userland/Libraries/LibWeb/Loader/ResourceLoader.cpp b/Userland/Libraries/LibWeb/Loader/ResourceLoader.cpp
index 845e9391ea..2f34922b28 100644
--- a/Userland/Libraries/LibWeb/Loader/ResourceLoader.cpp
+++ b/Userland/Libraries/LibWeb/Loader/ResourceLoader.cpp
@@ -285,7 +285,7 @@ void ResourceLoader::load(LoadRequest& request, Function<void(ReadonlyBytes, Has
 
         if (timeout.has_value() && timeout.value() > 0) {
             auto timer = Platform::Timer::create_single_shot(timeout.value(), nullptr);
-            timer->on_timeout = [timer, protocol_request, timeout_callback = move(timeout_callback)]() mutable {
+            timer->on_timeout = [timer, protocol_request, timeout_callback = move(timeout_callback)] {
                 protocol_request->stop();
                 if (timeout_callback)
                     timeout_callback();
diff --git a/Userland/Libraries/LibWeb/XML/XMLDocumentBuilder.cpp b/Userland/Libraries/LibWeb/XML/XMLDocumentBuilder.cpp
index 11f71d548c..dd808688d5 100644
--- a/Userland/Libraries/LibWeb/XML/XMLDocumentBuilder.cpp
+++ b/Userland/Libraries/LibWeb/XML/XMLDocumentBuilder.cpp
@@ -178,7 +178,7 @@ void XMLDocumentBuilder::document_end()
         (void)m_document.scripts_to_execute_when_parsing_has_finished().take_first();
     }
     // Queue a global task on the DOM manipulation task source given the Document's relevant global object to run the following substeps:
-    old_queue_global_task_with_document(HTML::Task::Source::DOMManipulation, m_document, [document = &m_document]() mutable {
+    old_queue_global_task_with_document(HTML::Task::Source::DOMManipulation, m_document, [document = &m_document] {
         // Set the Document's load timing info's DOM content loaded event start time to the current high resolution time given the Document's relevant global object.
         document->load_timing_info().dom_content_loaded_event_start_time = HighResolutionTime::unsafe_shared_current_time();
 
@@ -206,7 +206,7 @@ void XMLDocumentBuilder::document_end()
     });
 
     // Queue a global task on the DOM manipulation task source given the Document's relevant global object to run the following steps:
-    old_queue_global_task_with_document(HTML::Task::Source::DOMManipulation, m_document, [document = &m_document]() mutable {
+    old_queue_global_task_with_document(HTML::Task::Source::DOMManipulation, m_document, [document = &m_document] {
         // Update the current document readiness to "complete".
         document->update_readiness(HTML::DocumentReadyState::Complete);
 
diff --git a/Userland/Services/SQLServer/SQLStatement.cpp b/Userland/Services/SQLServer/SQLStatement.cpp
index 11b3068356..9ef3bb4bbc 100644
--- a/Userland/Services/SQLServer/SQLStatement.cpp
+++ b/Userland/Services/SQLServer/SQLStatement.cpp
@@ -60,7 +60,7 @@ void SQLStatement::execute()
         return;
     }
 
-    deferred_invoke([this]() mutable {
+    deferred_invoke([this] {
         auto parse_result = parse();
         if (parse_result.is_error()) {
             report_error(parse_result.release_error());
diff --git a/Userland/Services/WebDriver/Session.cpp b/Userland/Services/WebDriver/Session.cpp
index 7510425cb6..a96bb49819 100644
--- a/Userland/Services/WebDriver/Session.cpp
+++ b/Userland/Services/WebDriver/Session.cpp
@@ -36,7 +36,7 @@ ErrorOr<NonnullRefPtr<Core::LocalServer>> Session::create_server(String const& s
     auto server = TRY(Core::LocalServer::try_create());
     server->listen(socket_path);
 
-    server->on_accept = [this, promise](auto client_socket) mutable {
+    server->on_accept = [this, promise](auto client_socket) {
         auto maybe_connection = adopt_nonnull_ref_or_enomem(new (nothrow) WebContentConnection(move(client_socket), m_client, session_id()));
         if (maybe_connection.is_error()) {
             promise->resolve(maybe_connection.release_error());
@@ -49,7 +49,7 @@ ErrorOr<NonnullRefPtr<Core::LocalServer>> Session::create_server(String const& s
         promise->resolve({});
     };
 
-    server->on_accept_error = [promise](auto error) mutable {
+    server->on_accept_error = [promise](auto error) {
         promise->resolve(move(error));
     };
 
diff --git a/Userland/Services/WindowServer/ConnectionFromClient.cpp b/Userland/Services/WindowServer/ConnectionFromClient.cpp
index 6d8aefc7c1..f39ca5309d 100644
--- a/Userland/Services/WindowServer/ConnectionFromClient.cpp
+++ b/Userland/Services/WindowServer/ConnectionFromClient.cpp
@@ -234,7 +234,7 @@ void ConnectionFromClient::flash_menubar_menu(i32 window_id, i32 menu_id)
             m_flashed_menu_timer->stop();
         }
 
-        m_flashed_menu_timer = Core::Timer::create_single_shot(75, [weak_window = window.make_weak_ptr<Window>()]() mutable {
+        m_flashed_menu_timer = Core::Timer::create_single_shot(75, [weak_window = window.make_weak_ptr<Window>()] {
             if (!weak_window)
                 return;
             weak_window->menubar().flash_menu(nullptr);
diff --git a/Userland/Utilities/headless-browser.cpp b/Userland/Utilities/headless-browser.cpp
index b29ac61f2b..90e88902f3 100644
--- a/Userland/Utilities/headless-browser.cpp
+++ b/Userland/Utilities/headless-browser.cpp
@@ -327,7 +327,7 @@ public:
             , m_socket(move(socket))
             , m_job(HTTP::Job::construct(move(request), *m_output_stream))
         {
-            m_job->on_headers_received = [weak_this = make_weak_ptr()](auto& response_headers, auto response_code) mutable {
+            m_job->on_headers_received = [weak_this = make_weak_ptr()](auto& response_headers, auto response_code) {
                 if (auto strong_this = weak_this.strong_ref()) {
                     strong_this->m_response_code = response_code;
                     for (auto& header : response_headers) {
@@ -335,8 +335,8 @@ public:
                     }
                 }
             };
-            m_job->on_finish = [weak_this = make_weak_ptr()](bool success) mutable {
-                Core::deferred_invoke([weak_this, success]() mutable {
+            m_job->on_finish = [weak_this = make_weak_ptr()](bool success) {
+                Core::deferred_invoke([weak_this, success] {
                     if (auto strong_this = weak_this.strong_ref()) {
                         ReadonlyBytes response_bytes { strong_this->m_output_stream->bytes().data(), strong_this->m_output_stream->offset() };
                         auto response_buffer = ByteBuffer::copy(response_bytes).release_value_but_fixme_should_propagate_errors();
@@ -406,7 +406,7 @@ public:
             , m_socket(move(socket))
             , m_job(HTTP::HttpsJob::construct(move(request), *m_output_stream))
         {
-            m_job->on_headers_received = [weak_this = make_weak_ptr()](auto& response_headers, auto response_code) mutable {
+            m_job->on_headers_received = [weak_this = make_weak_ptr()](auto& response_headers, auto response_code) {
                 if (auto strong_this = weak_this.strong_ref()) {
                     strong_this->m_response_code = response_code;
                     for (auto& header : response_headers) {
@@ -414,8 +414,8 @@ public:
                     }
                 }
             };
-            m_job->on_finish = [weak_this = make_weak_ptr()](bool success) mutable {
-                Core::deferred_invoke([weak_this, success]() mutable {
+            m_job->on_finish = [weak_this = make_weak_ptr()](bool success) {
+                Core::deferred_invoke([weak_this, success] {
                     if (auto strong_this = weak_this.strong_ref()) {
                         ReadonlyBytes response_bytes { strong_this->m_output_stream->bytes().data(), strong_this->m_output_stream->offset() };
                         auto response_buffer = ByteBuffer::copy(response_bytes).release_value_but_fixme_should_propagate_errors();
@@ -475,7 +475,7 @@ public:
             , m_socket(move(socket))
             , m_job(Gemini::Job::construct(move(request), *m_output_stream))
         {
-            m_job->on_headers_received = [weak_this = make_weak_ptr()](auto& response_headers, auto response_code) mutable {
+            m_job->on_headers_received = [weak_this = make_weak_ptr()](auto& response_headers, auto response_code) {
                 if (auto strong_this = weak_this.strong_ref()) {
                     strong_this->m_response_code = response_code;
                     for (auto& header : response_headers) {
@@ -483,8 +483,8 @@ public:
                     }
                 }
             };
-            m_job->on_finish = [weak_this = make_weak_ptr()](bool success) mutable {
-                Core::deferred_invoke([weak_this, success]() mutable {
+            m_job->on_finish = [weak_this = make_weak_ptr()](bool success) {
+                Core::deferred_invoke([weak_this, success] {
                     if (auto strong_this = weak_this.strong_ref()) {
                         ReadonlyBytes response_bytes { strong_this->m_output_stream->bytes().data(), strong_this->m_output_stream->offset() };
                         auto response_buffer = ByteBuffer::copy(response_bytes).release_value_but_fixme_should_propagate_errors();
@@ -717,7 +717,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     dbgln("Taking screenshot after {} seconds !", take_screenshot_after);
     auto timer = Core::Timer::create_single_shot(
         take_screenshot_after * 1000,
-        [page_client = move(page_client)]() mutable {
+        [page_client = move(page_client)] {
             // FIXME: Allow passing the output path as argument
             String output_file_path = "output.png";
             dbgln("Saving to {}", output_file_path);