Userland: Silence or resolve new GCC 13 warnings

GCC 13 produces the following true positive warnings:
- `-Wredundant-move` when trying to move `result->tooltip()`, which
  is a const reference in `Assistant/main.cpp`
- `-Wuse-after-free` when freeing an environment variable before
  removing it from `s_malloced_environment_variables`
- `-Wdangling-pointer` when storing an AST node's `this` pointer to the
  interpreter's node stack in LibJS. This is not actually an issue, as
  it is popped when the scope ends, but GCC has no way of telling this.

3 files changed, 6 insertions, 2 deletions

diff --git a/Userland/Applications/Assistant/main.cpp b/Userland/Applications/Assistant/main.cpp
index 752eff40de..483e45464c 100644
--- a/Userland/Applications/Assistant/main.cpp
+++ b/Userland/Applications/Assistant/main.cpp
@@ -251,7 +251,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
             auto& match = results_container.add<Assistant::ResultRow>();
             match.set_icon(result->bitmap());
             match.set_text(String::from_deprecated_string(result->title()).release_value_but_fixme_should_propagate_errors());
-            match.set_tooltip(move(result->tooltip()));
+            match.set_tooltip(result->tooltip());
             match.on_click = [&result](auto) {
                 result->activate();
                 GUI::Application::the()->quit();
diff --git a/Userland/Libraries/LibC/stdlib.cpp b/Userland/Libraries/LibC/stdlib.cpp
index 687de3a7a3..8e006129e0 100644
--- a/Userland/Libraries/LibC/stdlib.cpp
+++ b/Userland/Libraries/LibC/stdlib.cpp
@@ -399,8 +399,8 @@ static void free_environment_variable_if_needed(char const* var)
 {
     if (!s_malloced_environment_variables.contains((FlatPtr)var))
         return;
-    free(const_cast<char*>(var));
     s_malloced_environment_variables.remove((FlatPtr)var);
+    free(const_cast<char*>(var));
 }
 
 char* getenv(char const* name)
diff --git a/Userland/Libraries/LibJS/AST.cpp b/Userland/Libraries/LibJS/AST.cpp
index 4a5c4f5626..09e8663230 100644
--- a/Userland/Libraries/LibJS/AST.cpp
+++ b/Userland/Libraries/LibJS/AST.cpp
@@ -48,7 +48,11 @@ public:
         , m_chain_node { nullptr, node }
     {
         m_interpreter.vm().running_execution_context().current_node = &node;
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wdangling-pointer"
+        // The node pointer is popped from the interpreter in the destructor.
         m_interpreter.push_ast_node(m_chain_node);
+#pragma GCC diagnostic push
     }
 
     ~InterpreterNodeScope()