LibWeb: Start implementing "create and initialize a Document" from HTML

The way we've been creating DOM::Document has been pretty far from what
the spec tells us to do, and this is a first big step towards getting us
closer to spec.

The new Document::create_and_initialize() is called by FrameLoader after
loading a "text/html" resource.

We create the JS Realm and the Window object when creating the Document
(previously, we'd do it on first access to Document::interpreter().)

The realm execution context is owned by the Environment Settings Object.

13 files changed, 318 insertions, 81 deletions

diff --git a/Userland/Libraries/LibWeb/Bindings/MainThreadVM.cpp b/Userland/Libraries/LibWeb/Bindings/MainThreadVM.cpp
index 57cbd7501e..27e24424d2 100644
--- a/Userland/Libraries/LibWeb/Bindings/MainThreadVM.cpp
+++ b/Userland/Libraries/LibWeb/Bindings/MainThreadVM.cpp
@@ -366,4 +366,28 @@ void queue_mutation_observer_microtask(DOM::Document& document)
     });
 }
 
+// https://html.spec.whatwg.org/multipage/webappapis.html#creating-a-new-javascript-realm
+NonnullOwnPtr<JS::ExecutionContext> create_a_new_javascript_realm(JS::VM& vm, Function<JS::Value(JS::Realm&)> create_global_object, Function<JS::Value(JS::Realm&)> create_global_this_value)
+{
+    // 1. Perform InitializeHostDefinedRealm() with the provided customizations for creating the global object and the global this binding.
+    // 2. Let realm execution context be the running JavaScript execution context.
+    auto realm_execution_context = MUST(JS::Realm::initialize_host_defined_realm(vm, move(create_global_object), move(create_global_this_value)));
+
+    // 3. Remove realm execution context from the JavaScript execution context stack.
+    vm.execution_context_stack().remove_first_matching([&realm_execution_context](auto* execution_context) {
+        return execution_context == realm_execution_context.ptr();
+    });
+
+    // NO-OP: 4. Let realm be realm execution context's Realm component.
+    // NO-OP: 5. Set realm's agent to agent.
+
+    // FIXME: 6. If agent's agent cluster's cross-origin isolation mode is "none", then:
+    //          1. Let global be realm's global object.
+    //          2. Let status be ! global.[[Delete]]("SharedArrayBuffer").
+    //          3. Assert: status is true.
+
+    // 7. Return realm execution context.
+    return realm_execution_context;
+}
+
 }
diff --git a/Userland/Libraries/LibWeb/Bindings/MainThreadVM.h b/Userland/Libraries/LibWeb/Bindings/MainThreadVM.h
index 686ce3ccb1..cea1de14ee 100644
--- a/Userland/Libraries/LibWeb/Bindings/MainThreadVM.h
+++ b/Userland/Libraries/LibWeb/Bindings/MainThreadVM.h
@@ -49,5 +49,6 @@ struct WebEngineCustomJobCallbackData final : public JS::JobCallback::CustomData
 HTML::ClassicScript* active_script();
 JS::VM& main_thread_vm();
 void queue_mutation_observer_microtask(DOM::Document&);
+NonnullOwnPtr<JS::ExecutionContext> create_a_new_javascript_realm(JS::VM&, Function<JS::Value(JS::Realm&)> create_global_object, Function<JS::Value(JS::Realm&)> create_global_this_value);
 
 }
diff --git a/Userland/Libraries/LibWeb/DOM/Document.cpp b/Userland/Libraries/LibWeb/DOM/Document.cpp
index cd638ac93f..454a3945e2 100644
--- a/Userland/Libraries/LibWeb/DOM/Document.cpp
+++ b/Userland/Libraries/LibWeb/DOM/Document.cpp
@@ -56,6 +56,7 @@
 #include <LibWeb/HTML/HTMLScriptElement.h>
 #include <LibWeb/HTML/HTMLTitleElement.h>
 #include <LibWeb/HTML/MessageEvent.h>
+#include <LibWeb/HTML/NavigationParams.h>
 #include <LibWeb/HTML/Origin.h>
 #include <LibWeb/HTML/Parser/HTMLParser.h>
 #include <LibWeb/HTML/Scripting/ExceptionReporter.h>
@@ -74,6 +75,196 @@
 
 namespace Web::DOM {
 
+// https://html.spec.whatwg.org/multipage/origin.html#obtain-browsing-context-navigation
+static NonnullRefPtr<HTML::BrowsingContext> obtain_a_browsing_context_to_use_for_a_navigation_response(
+    HTML::BrowsingContext& browsing_context,
+    HTML::SandboxingFlagSet sandbox_flags,
+    HTML::CrossOriginOpenerPolicy navigation_coop,
+    HTML::CrossOriginOpenerPolicyEnforcementResult coop_enforcement_result)
+{
+    // 1. If browsingContext is not a top-level browsing context, return browsingContext.
+    if (!browsing_context.is_top_level())
+        return browsing_context;
+
+    // 2. If coopEnforcementResult's needs a browsing context group switch is false, then:
+    if (!coop_enforcement_result.needs_a_browsing_context_group_switch) {
+        // 1. If coopEnforcementResult's would need a browsing context group switch due to report-only is true,
+        if (coop_enforcement_result.would_need_a_browsing_context_group_switch_due_to_report_only) {
+            // FIXME: set browsing context's virtual browsing context group ID to a new unique identifier.
+        }
+        // 2. Return browsingContext.
+        return browsing_context;
+    }
+
+    // 3. Let newBrowsingContext be the result of creating a new top-level browsing context.
+    VERIFY(browsing_context.page());
+    auto new_browsing_context = HTML::BrowsingContext::create_a_new_browsing_context(*browsing_context.page(), nullptr, nullptr);
+
+    // FIXME: 4. If navigationCOOP's value is "same-origin-plus-COEP", then set newBrowsingContext's group's
+    //           cross-origin isolation mode to either "logical" or "concrete". The choice of which is implementation-defined.
+
+    // 5. If sandboxFlags is not empty, then:
+    if (!sandbox_flags.is_empty()) {
+        // 1. Assert navigationCOOP's value is "unsafe-none".
+        VERIFY(navigation_coop.value == HTML::CrossOriginOpenerPolicyValue::UnsafeNone);
+
+        // 2. Assert: newBrowsingContext's popup sandboxing flag set is empty.
+
+        // 3. Set newBrowsingContext's popup sandboxing flag set to a clone of sandboxFlags.
+    }
+
+    // FIXME: 6. Discard browsingContext.
+
+    // 7. Return newBrowsingContext.
+    return new_browsing_context;
+}
+
+// https://html.spec.whatwg.org/multipage/browsing-the-web.html#initialise-the-document-object
+NonnullRefPtr<Document> Document::create_and_initialize(Type type, String content_type, HTML::NavigationParams navigation_params)
+{
+    // 1. Let browsingContext be the result of the obtaining a browsing context to use for a navigation response
+    //    given navigationParams's browsing context, navigationParams's final sandboxing flag set,
+    //    navigationParams's cross-origin opener policy, and navigationParams's COOP enforcement result.
+    auto browsing_context = obtain_a_browsing_context_to_use_for_a_navigation_response(
+        navigation_params.browsing_context,
+        navigation_params.final_sandboxing_flag_set,
+        navigation_params.cross_origin_opener_policy,
+        navigation_params.coop_enforcement_result);
+
+    // FIXME: 2. Let permissionsPolicy be the result of creating a permissions policy from a response
+    //           given browsingContext, navigationParams's origin, and navigationParams's response.
+
+    // 3. Let creationURL be navigationParams's response's URL.
+    auto creation_url = navigation_params.response->url();
+
+    // 4. If navigationParams's request is non-null, then set creationURL to navigationParams's request's current URL.
+    if (navigation_params.request) {
+        creation_url = navigation_params.request->current_url();
+    }
+
+    RefPtr<HTML::Window> window;
+
+    // 5. If browsingContext is still on its initial about:blank Document,
+    //    and navigationParams's history handling is "replace",
+    //    and browsingContext's active document's origin is same origin-domain with navigationParams's origin,
+    //    then do nothing.
+    if (browsing_context->still_on_its_initial_about_blank_document()
+        && navigation_params.history_handling == HTML::HistoryHandlingBehavior::Replace
+        && (browsing_context->active_document() && browsing_context->active_document()->origin().is_same_origin(navigation_params.origin))) {
+        // Do nothing.
+    }
+
+    // 6. Otherwise:
+    else {
+        // FIXME: 1. Let oacHeader be the result of getting a structured field value given `Origin-Agent-Cluster` and "item" from response's header list.
+
+        // FIXME: 2. Let requestsOAC be true if oacHeader is not null and oacHeader[0] is the boolean true; otherwise false.
+        [[maybe_unused]] auto requests_oac = false;
+
+        // FIXME: 3. If navigationParams's reserved environment is a non-secure context, then set requestsOAC to false.
+
+        // FIXME: 4. Let agent be the result of obtaining a similar-origin window agent given navigationParams's origin, browsingContext's group, and requestsOAC.
+
+        // 5. Let realm execution context be the result of creating a new JavaScript realm given agent and the following customizations:
+        auto realm_execution_context = Bindings::create_a_new_javascript_realm(
+            Bindings::main_thread_vm(),
+            [&](JS::Realm& realm) -> JS::Value {
+                // - For the global object, create a new Window object.
+                window = HTML::Window::create();
+                auto* global_object = realm.heap().allocate_without_global_object<Bindings::WindowObject>(realm, *window);
+                VERIFY(window->wrapper() == global_object);
+                return global_object;
+            },
+            [](JS::Realm&) -> JS::Value {
+                // FIXME: - For the global this binding, use browsingContext's WindowProxy object.
+                return JS::js_undefined();
+            });
+
+        // 6. Let topLevelCreationURL be creationURL.
+        auto top_level_creation_url = creation_url;
+
+        // 7. Let topLevelOrigin be navigationParams's origin.
+        auto top_level_origin = navigation_params.origin;
+
+        // 8. If browsingContext is not a top-level browsing context, then:
+        if (!browsing_context->is_top_level()) {
+            // 1. Let parentEnvironment be browsingContext's container's relevant settings object.
+            auto& parent_environment = browsing_context->container()->document().relevant_settings_object();
+
+            // 2. Set topLevelCreationURL to parentEnvironment's top-level creation URL.
+            top_level_creation_url = parent_environment.top_level_creation_url;
+
+            // 3. Set topLevelOrigin to parentEnvironment's top-level origin.
+            top_level_origin = parent_environment.top_level_origin;
+        }
+
+        // 9. Set up a window environment settings object with creationURL, realm execution context,
+        //    navigationParams's reserved environment, topLevelCreationURL, and topLevelOrigin.
+
+        // FIXME: Why do we assume `creation_url` is non-empty here? Is this a spec bug?
+        // FIXME: Why do we assume `top_level_creation_url` is non-empty here? Is this a spec bug?
+        HTML::WindowEnvironmentSettingsObject::setup(
+            creation_url.value(),
+            move(realm_execution_context),
+            navigation_params.reserved_environment,
+            top_level_creation_url.value(),
+            top_level_origin);
+    }
+
+    // FIXME: 7. Let loadTimingInfo be a new document load timing info with its navigation start time set to response's timing info's start time.
+
+    // 8. Let document be a new Document,
+    //    whose type is type,
+    //    content type is contentType,
+    //    FIXME: origin is navigationParams's origin,
+    //    FIXME: policy container is navigationParams's policy container,
+    //    FIXME: permissions policy is permissionsPolicy,
+    //    FIXME: active sandboxing flag set is navigationParams's final sandboxing flag set,
+    //    FIXME: and cross-origin opener policy is navigationParams's cross-origin opener policy,
+    //    FIXME: load timing info is loadTimingInfo,
+    //    FIXME: and navigation id is navigationParams's id.
+    auto document = Document::create();
+    document->m_type = type;
+    document->m_content_type = content_type;
+
+    document->m_window = window;
+    window->set_associated_document(*document);
+
+    // 9. Set document's URL to creationURL.
+    document->m_url = creation_url.value();
+
+    // 10. Set document's current document readiness to "loading".
+    document->m_readiness = HTML::DocumentReadyState::Loading;
+
+    // FIXME: 11. Run CSP initialization for a Document given document.
+
+    // 12. If navigationParams's request is non-null, then:
+    if (navigation_params.request) {
+        // FIXME: 1. Set document's referrer to the empty string.
+        // FIXME: 2. Let referrer be navigationParams's request's referrer.
+        // FIXME: 3. If referrer is a URL record, then set document's referrer to the serialization of referrer.
+    }
+
+    // FIXME: 13. Let historyHandling be navigationParams's history handling.
+
+    // FIXME: 14: Let navigationTimingType be the result of switching on navigationParams's history handling...
+
+    // FIXME: 15. Let redirectCount be 0 if navigationParams's has cross-origin redirects is true;
+    //            otherwise navigationParams's request's redirect count.
+
+    // FIXME: 16. Create the navigation timing entry for document, with navigationParams's response's timing info,
+    //            redirectCount, navigationTimingType, and navigationParams's response's service worker timing info.
+
+    // FIXME: 17. If navigationParams's response has a `Refresh` header, then...
+
+    // FIXME: 18. If navigationParams's commit early hints is not null, then call navigationParams's commit early hints with document.
+
+    // FIXME: 19. Process link headers given document, navigationParams's response, and "pre-media".
+
+    // 20. Return document.
+    return document;
+}
+
 NonnullRefPtr<Document> Document::create_with_global_object(Bindings::WindowObject&)
 {
     return Document::create();
@@ -891,52 +1082,16 @@ HTML::EnvironmentSettingsObject& Document::relevant_settings_object()
 
 JS::Realm& Document::realm()
 {
-    return interpreter().realm();
+    VERIFY(m_window);
+    VERIFY(m_window->wrapper());
+    VERIFY(m_window->wrapper()->associated_realm());
+    return *m_window->wrapper()->associated_realm();
 }
 
 JS::Interpreter& Document::interpreter()
 {
     if (!m_interpreter) {
-        // FIXME: This is all ad-hoc. It loosely follows steps 6.4 to 6.9 of https://html.spec.whatwg.org/#initialise-the-document-object
-        auto& vm = Bindings::main_thread_vm();
-
-        // https://html.spec.whatwg.org/multipage/webappapis.html#creating-a-new-javascript-realm
-        // FIXME: Put all this into it's own function that can be used outside of Document.
-
-        // 1. Perform InitializeHostDefinedRealm() with the provided customizations for creating the global object and the global this binding.
-        // FIXME: Use WindowProxy as the global this value.
-        m_interpreter = JS::Interpreter::create<Bindings::WindowObject>(vm, *m_window);
-
-        // 2. Let realm execution context be the running JavaScript execution context.
-        auto& realm_execution_context = vm.running_execution_context();
-
-        // 3. Remove realm execution context from the JavaScript execution context stack.
-        vm.execution_context_stack().remove_first_matching([&realm_execution_context](auto* execution_context) {
-            return execution_context == &realm_execution_context;
-        });
-
-        // FIXME: 4. Let realm be realm execution context's Realm component.
-        // FIXME: 5. Set realm's agent to agent.
-
-        // FIXME: 6. If agent's agent cluster's cross-origin isolation mode is "none", then:
-        //          1. Let global be realm's global object.
-        //          2. Let status be ! global.[[Delete]]("SharedArrayBuffer").
-        //          3. Assert: status is true.
-
-        // FIXME: 7. Return realm execution context. (Requires being in it's own function as mentioned above)
-
-        // == End of "create a JavaScript realm" ==
-
-        // FIXME: 6. Let topLevelCreationURL be creationURL.
-        // FIXME: 7. Let topLevelOrigin be navigationParams's origin.
-        // FIXME: 8. If browsingContext is not a top-level browsing context, then:
-        //          1. Let parentEnvironment be browsingContext's container's relevant settings object.
-        //          2. Set topLevelCreationURL to parentEnvironment's top-level creation URL.
-        //          3. Set topLevelOrigin to parentEnvironment's top-level origin.
-
-        // FIXME: 9. Set up a window environment settings object with creationURL, realm execution context, navigationParams's reserved environment, topLevelCreationURL, and topLevelOrigin.
-        //        (This is missing reserved environment, topLevelCreationURL and topLevelOrigin. It also assumes creationURL is the document's URL, when it's really "navigationParams's response's URL.")
-        HTML::WindowEnvironmentSettingsObject::setup(m_url, realm_execution_context);
+        m_interpreter = JS::Interpreter::create_with_existing_realm(realm());
     }
     return *m_interpreter;
 }
diff --git a/Userland/Libraries/LibWeb/DOM/Document.h b/Userland/Libraries/LibWeb/DOM/Document.h
index 51409d8dab..f71b88e13a 100644
--- a/Userland/Libraries/LibWeb/DOM/Document.h
+++ b/Userland/Libraries/LibWeb/DOM/Document.h
@@ -51,6 +51,8 @@ public:
         HTML
     };
 
+    static NonnullRefPtr<Document> create_and_initialize(Type, String content_type, HTML::NavigationParams);
+
     static NonnullRefPtr<Document> create(AK::URL const& url = "about:blank"sv);
     static NonnullRefPtr<Document> create_with_global_object(Bindings::WindowObject&);
     virtual ~Document() override;
diff --git a/Userland/Libraries/LibWeb/Forward.h b/Userland/Libraries/LibWeb/Forward.h
index 6836e00911..0db319a442 100644
--- a/Userland/Libraries/LibWeb/Forward.h
+++ b/Userland/Libraries/LibWeb/Forward.h
@@ -202,6 +202,8 @@ class BrowsingContextContainer;
 class CanvasRenderingContext2D;
 class ClassicScript;
 class CloseEvent;
+struct CrossOriginOpenerPolicy;
+struct CrossOriginOpenerPolicyEnforcementResult;
 class DOMParser;
 class DOMStringMap;
 struct Environment;
@@ -287,11 +289,13 @@ class ImageData;
 class MessageChannel;
 class MessageEvent;
 class MessagePort;
+struct NavigationParams;
 class Origin;
 class PageTransitionEvent;
 struct PolicyContainer;
 class PromiseRejectionEvent;
 class WorkerDebugConsoleClient;
+struct SandboxingFlagSet;
 class Storage;
 class SubmitEvent;
 class TextMetrics;
diff --git a/Userland/Libraries/LibWeb/HTML/Scripting/Environments.cpp b/Userland/Libraries/LibWeb/HTML/Scripting/Environments.cpp
index da1945f979..4cbeb56f75 100644
--- a/Userland/Libraries/LibWeb/HTML/Scripting/Environments.cpp
+++ b/Userland/Libraries/LibWeb/HTML/Scripting/Environments.cpp
@@ -16,8 +16,8 @@
 
 namespace Web::HTML {
 
-EnvironmentSettingsObject::EnvironmentSettingsObject(JS::ExecutionContext& realm_execution_context)
-    : m_realm_execution_context(realm_execution_context)
+EnvironmentSettingsObject::EnvironmentSettingsObject(NonnullOwnPtr<JS::ExecutionContext> realm_execution_context)
+    : m_realm_execution_context(move(realm_execution_context))
 {
     // Register with the responsible event loop so we can perform step 4 of "perform a microtask checkpoint".
     responsible_event_loop().register_environment_settings_object({}, *this);
@@ -31,7 +31,7 @@ EnvironmentSettingsObject::~EnvironmentSettingsObject()
 JS::ExecutionContext& EnvironmentSettingsObject::realm_execution_context()
 {
     // NOTE: All environment settings objects are created with a realm execution context, so it's stored and returned here in the base class.
-    return m_realm_execution_context;
+    return *m_realm_execution_context;
 }
 
 // https://html.spec.whatwg.org/multipage/webappapis.html#environment-settings-object%27s-realm
diff --git a/Userland/Libraries/LibWeb/HTML/Scripting/Environments.h b/Userland/Libraries/LibWeb/HTML/Scripting/Environments.h
index e884af750a..314a3297d5 100644
--- a/Userland/Libraries/LibWeb/HTML/Scripting/Environments.h
+++ b/Userland/Libraries/LibWeb/HTML/Scripting/Environments.h
@@ -105,10 +105,10 @@ struct EnvironmentSettingsObject
     bool is_scripting_disabled() const;
 
 protected:
-    explicit EnvironmentSettingsObject(JS::ExecutionContext& realm_execution_context);
+    explicit EnvironmentSettingsObject(NonnullOwnPtr<JS::ExecutionContext>);
 
 private:
-    JS::ExecutionContext& m_realm_execution_context;
+    NonnullOwnPtr<JS::ExecutionContext> m_realm_execution_context;
     EventLoop* m_responsible_event_loop { nullptr };
 
     // https://html.spec.whatwg.org/multipage/webappapis.html#outstanding-rejected-promises-weak-set
diff --git a/Userland/Libraries/LibWeb/HTML/Scripting/WindowEnvironmentSettingsObject.cpp b/Userland/Libraries/LibWeb/HTML/Scripting/WindowEnvironmentSettingsObject.cpp
index bc5183fce2..e5b6c8e636 100644
--- a/Userland/Libraries/LibWeb/HTML/Scripting/WindowEnvironmentSettingsObject.cpp
+++ b/Userland/Libraries/LibWeb/HTML/Scripting/WindowEnvironmentSettingsObject.cpp
@@ -10,17 +10,17 @@
 
 namespace Web::HTML {
 
-WindowEnvironmentSettingsObject::WindowEnvironmentSettingsObject(Window& window, JS::ExecutionContext& execution_context)
-    : EnvironmentSettingsObject(execution_context)
+WindowEnvironmentSettingsObject::WindowEnvironmentSettingsObject(Window& window, NonnullOwnPtr<JS::ExecutionContext> execution_context)
+    : EnvironmentSettingsObject(move(execution_context))
     , m_window(window)
 {
 }
 
 // https://html.spec.whatwg.org/multipage/window-object.html#set-up-a-window-environment-settings-object
-void WindowEnvironmentSettingsObject::setup(AK::URL& creation_url, JS::ExecutionContext& execution_context)
+void WindowEnvironmentSettingsObject::setup(AK::URL const& creation_url, NonnullOwnPtr<JS::ExecutionContext> execution_context, Optional<Environment> reserved_environment, AK::URL top_level_creation_url, Origin top_level_origin)
 {
     // 1. Let realm be the value of execution context's Realm component.
-    auto* realm = execution_context.realm;
+    auto* realm = execution_context->realm;
     VERIFY(realm);
 
     // 2. Let window be realm's global object.
@@ -29,17 +29,32 @@ void WindowEnvironmentSettingsObject::setup(AK::URL& creation_url, JS::Execution
 
     // 3. Let settings object be a new environment settings object whose algorithms are defined as follows:
     // NOTE: See the functions defined for this class.
-    auto settings_object = adopt_own(*new WindowEnvironmentSettingsObject(window, execution_context));
-
-    // FIXME: 4. If reservedEnvironment is non-null, then:
-    // FIXME:    1. Set settings object's id to reservedEnvironment's id, target browsing context to reservedEnvironment's target browsing context, and active service worker to reservedEnvironment's active service worker.
-    // FIXME:    2. Set reservedEnvironment's id to the empty string.
-
-    // FIXME: 5. Otherwise, set settings object's id to a new unique opaque string, settings object's target browsing context to null, and settings object's active service worker to null.
-    settings_object->target_browsing_context = nullptr;
-
-    // FIXME: 6. Set settings object's creation URL to creationURL, settings object's top-level creation URL to topLevelCreationURL, and settings object's top-level origin to topLevelOrigin.
+    auto settings_object = adopt_own(*new WindowEnvironmentSettingsObject(window, move(execution_context)));
+
+    // 4. If reservedEnvironment is non-null, then:
+    if (reserved_environment.has_value()) {
+        // FIXME:    1. Set settings object's id to reservedEnvironment's id,
+        //              target browsing context to reservedEnvironment's target browsing context,
+        //              and active service worker to reservedEnvironment's active service worker.
+        settings_object->target_browsing_context = reserved_environment->target_browsing_context;
+
+        // FIXME:    2. Set reservedEnvironment's id to the empty string.
+    }
+
+    // 5. Otherwise, ...
+    else {
+        // FIXME: ...set settings object's id to a new unique opaque string,
+        //        settings object's target browsing context to null,
+        //        and settings object's active service worker to null.
+        settings_object->target_browsing_context = nullptr;
+    }
+
+    // 6. Set settings object's creation URL to creationURL,
+    //    settings object's top-level creation URL to topLevelCreationURL,
+    //    and settings object's top-level origin to topLevelOrigin.
     settings_object->creation_url = creation_url;
+    settings_object->top_level_creation_url = top_level_creation_url;
+    settings_object->top_level_origin = top_level_origin;
 
     // 7. Set realm's [[HostDefined]] field to settings object.
     realm->set_host_defined(move(settings_object));
diff --git a/Userland/Libraries/LibWeb/HTML/Scripting/WindowEnvironmentSettingsObject.h b/Userland/Libraries/LibWeb/HTML/Scripting/WindowEnvironmentSettingsObject.h
index e891c4f2bf..f15a2397e1 100644
--- a/Userland/Libraries/LibWeb/HTML/Scripting/WindowEnvironmentSettingsObject.h
+++ b/Userland/Libraries/LibWeb/HTML/Scripting/WindowEnvironmentSettingsObject.h
@@ -13,7 +13,7 @@ namespace Web::HTML {
 
 class WindowEnvironmentSettingsObject final : public EnvironmentSettingsObject {
 public:
-    static void setup(AK::URL& creation_url, JS::ExecutionContext& execution_context /* FIXME: null or an environment reservedEnvironment, a URL topLevelCreationURL, and an origin topLevelOrigin */);
+    static void setup(AK::URL const& creation_url, NonnullOwnPtr<JS::ExecutionContext>, Optional<Environment>, AK::URL top_level_creation_url, Origin top_level_origin);
 
     virtual ~WindowEnvironmentSettingsObject() override = default;
 
@@ -24,7 +24,7 @@ public:
     virtual CanUseCrossOriginIsolatedAPIs cross_origin_isolated_capability() override;
 
 private:
-    WindowEnvironmentSettingsObject(Window&, JS::ExecutionContext& execution_context);
+    WindowEnvironmentSettingsObject(Window&, NonnullOwnPtr<JS::ExecutionContext>);
 
     NonnullRefPtr<Window> m_window;
 };
diff --git a/Userland/Libraries/LibWeb/HTML/Scripting/WorkerEnvironmentSettingsObject.h b/Userland/Libraries/LibWeb/HTML/Scripting/WorkerEnvironmentSettingsObject.h
index 0dd1e32657..e4ea62459a 100644
--- a/Userland/Libraries/LibWeb/HTML/Scripting/WorkerEnvironmentSettingsObject.h
+++ b/Userland/Libraries/LibWeb/HTML/Scripting/WorkerEnvironmentSettingsObject.h
@@ -18,17 +18,17 @@ class WorkerEnvironmentSettingsObject final
     : public EnvironmentSettingsObject
     , public Weakable<WorkerEnvironmentSettingsObject> {
 public:
-    WorkerEnvironmentSettingsObject(DOM::Document& document, JS::ExecutionContext& execution_context)
-        : EnvironmentSettingsObject(execution_context)
+    WorkerEnvironmentSettingsObject(DOM::Document& document, NonnullOwnPtr<JS::ExecutionContext> execution_context)
+        : EnvironmentSettingsObject(move(execution_context))
         , m_document(document)
     {
     }
 
-    static WeakPtr<WorkerEnvironmentSettingsObject> setup(DOM::Document& document, JS::ExecutionContext& execution_context /* FIXME: null or an environment reservedEnvironment, a URL topLevelCreationURL, and an origin topLevelOrigin */)
+    static WeakPtr<WorkerEnvironmentSettingsObject> setup(DOM::Document& document, NonnullOwnPtr<JS::ExecutionContext> execution_context /* FIXME: null or an environment reservedEnvironment, a URL topLevelCreationURL, and an origin topLevelOrigin */)
     {
-        auto* realm = execution_context.realm;
+        auto* realm = execution_context->realm;
         VERIFY(realm);
-        auto settings_object = adopt_own(*new WorkerEnvironmentSettingsObject(document, execution_context));
+        auto settings_object = adopt_own(*new WorkerEnvironmentSettingsObject(document, move(execution_context)));
         settings_object->target_browsing_context = nullptr;
         realm->set_host_defined(move(settings_object));
 
diff --git a/Userland/Libraries/LibWeb/HTML/Worker.cpp b/Userland/Libraries/LibWeb/HTML/Worker.cpp
index 55cebc5afd..f8ee7b36b7 100644
--- a/Userland/Libraries/LibWeb/HTML/Worker.cpp
+++ b/Userland/Libraries/LibWeb/HTML/Worker.cpp
@@ -24,7 +24,6 @@ Worker::Worker(FlyString const& script_url, WorkerOptions const options, DOM::Do
     , m_worker_vm(JS::VM::create(adopt_own(m_custom_data)))
     , m_interpreter(JS::Interpreter::create<JS::GlobalObject>(m_worker_vm))
     , m_interpreter_scope(*m_interpreter)
-    , m_execution_context(m_worker_vm->heap())
     , m_implicit_port(MessagePort::create())
 {
 }
@@ -153,22 +152,23 @@ void Worker::run_a_worker(AK::URL& url, EnvironmentSettingsObject& outside_setti
 
     // FIXME: This is because I don't know all the libraries well enough to properly setup the environment to spec
     // let alone making it a parallel implementation.
-    m_execution_context.current_node = nullptr;
-    m_execution_context.this_value = m_worker_scope;
-    m_execution_context.function_name = "(global execution context)"sv;
-    m_execution_context.lexical_environment = &m_worker_realm->global_environment();
-    m_execution_context.variable_environment = &m_worker_realm->global_environment();
-    m_execution_context.realm = m_worker_realm;
+    auto execution_context = make<JS::ExecutionContext>(m_worker_vm->heap());
+    execution_context->current_node = nullptr;
+    execution_context->this_value = m_worker_scope;
+    execution_context->function_name = "(global execution context)"sv;
+    execution_context->lexical_environment = &m_worker_realm->global_environment();
+    execution_context->variable_environment = &m_worker_realm->global_environment();
+    execution_context->realm = m_worker_realm;
 
-    m_worker_vm->push_execution_context(m_execution_context);
-    m_worker_realm->set_global_object(*m_worker_scope, m_worker_scope);
+    m_worker_vm->push_execution_context(*execution_context);
+    m_worker_realm->set_global_object(m_worker_scope, m_worker_scope);
 
     // 8. Let worker global scope be the global object of realm execution context's Realm component.
     // NOTE: This is the DedicatedWorkerGlobalScope or SharedWorkerGlobalScope object created in the previous step.
 
     // 9. Set up a worker environment settings object with realm execution context,
     //    outside settings, and unsafeWorkerCreationTime, and let inside settings be the result.
-    m_inner_settings = WorkerEnvironmentSettingsObject::setup(*m_document, m_execution_context);
+    m_inner_settings = WorkerEnvironmentSettingsObject::setup(*m_document, move(execution_context));
 
     // 10. Set worker global scope's name to the value of options's name member.
     // FIXME: name property requires the SharedWorkerGlobalScope or DedicatedWorkerGlobalScope child class to be used
diff --git a/Userland/Libraries/LibWeb/HTML/Worker.h b/Userland/Libraries/LibWeb/HTML/Worker.h
index cf3ec36196..f37ff1014a 100644
--- a/Userland/Libraries/LibWeb/HTML/Worker.h
+++ b/Userland/Libraries/LibWeb/HTML/Worker.h
@@ -88,7 +88,6 @@ private:
     NonnullOwnPtr<JS::Interpreter> m_interpreter;
     WeakPtr<WorkerEnvironmentSettingsObject> m_inner_settings;
     JS::VM::InterpreterExecutionScope m_interpreter_scope;
-    JS::ExecutionContext m_execution_context;
     WeakPtr<JS::Realm> m_worker_realm;
     RefPtr<WorkerDebugConsoleClient> m_console;
     JS::GlobalObject* m_worker_scope;
diff --git a/Userland/Libraries/LibWeb/Loader/FrameLoader.cpp b/Userland/Libraries/LibWeb/Loader/FrameLoader.cpp
index 02d70cdecf..6343f1f7dc 100644
--- a/Userland/Libraries/LibWeb/Loader/FrameLoader.cpp
+++ b/Userland/Libraries/LibWeb/Loader/FrameLoader.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2020, Andreas Kling <kling@serenityos.org>
+ * Copyright (c) 2020-2022, Andreas Kling <kling@serenityos.org>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
@@ -17,6 +17,7 @@
 #include <LibWeb/DOM/Text.h>
 #include <LibWeb/HTML/BrowsingContext.h>
 #include <LibWeb/HTML/HTMLIFrameElement.h>
+#include <LibWeb/HTML/NavigationParams.h>
 #include <LibWeb/HTML/Parser/HTMLParser.h>
 #include <LibWeb/ImageDecoding.h>
 #include <LibWeb/Loader/FrameLoader.h>
@@ -253,7 +254,25 @@ bool FrameLoader::load(const AK::URL& url, Type type)
 
 void FrameLoader::load_html(StringView html, const AK::URL& url)
 {
-    auto document = DOM::Document::create(url);
+    auto response = make<Fetch::Infrastructure::Response>();
+    response->url_list().append(url);
+    HTML::NavigationParams navigation_params {
+        .id = {},
+        .request = nullptr,
+        .response = move(response),
+        .origin = HTML::Origin {},
+        .policy_container = HTML::PolicyContainer {},
+        .final_sandboxing_flag_set = HTML::SandboxingFlagSet {},
+        .cross_origin_opener_policy = HTML::CrossOriginOpenerPolicy {},
+        .coop_enforcement_result = HTML::CrossOriginOpenerPolicyEnforcementResult {},
+        .reserved_environment = {},
+        .browsing_context = browsing_context(),
+    };
+    auto document = DOM::Document::create_and_initialize(
+        DOM::Document::Type::HTML,
+        "text/html",
+        move(navigation_params));
+
     auto parser = HTML::HTMLParser::create(document, html, "utf-8");
     parser->run(url);
     browsing_context().set_active_document(&parser->document());
@@ -348,7 +367,25 @@ void FrameLoader::resource_did_load()
         dbgln_if(RESOURCE_DEBUG, "This content has MIME type '{}', encoding unknown", resource()->mime_type());
     }
 
-    auto document = DOM::Document::create();
+    auto response = make<Fetch::Infrastructure::Response>();
+    response->url_list().append(url);
+    HTML::NavigationParams navigation_params {
+        .id = {},
+        .request = nullptr,
+        .response = move(response),
+        .origin = HTML::Origin {},
+        .policy_container = HTML::PolicyContainer {},
+        .final_sandboxing_flag_set = HTML::SandboxingFlagSet {},
+        .cross_origin_opener_policy = HTML::CrossOriginOpenerPolicy {},
+        .coop_enforcement_result = HTML::CrossOriginOpenerPolicyEnforcementResult {},
+        .reserved_environment = {},
+        .browsing_context = browsing_context(),
+    };
+    auto document = DOM::Document::create_and_initialize(
+        DOM::Document::Type::HTML,
+        "text/html",
+        move(navigation_params));
+
     document->set_url(url);
     document->set_encoding(resource()->encoding());
     document->set_content_type(resource()->mime_type());