LibWeb: Fix some GCVerifier warnings

Author: https://github.com/mattco98
Commit: 8450041b52
Pull-request: https://github.com/SerenityOS/serenity/pull/23861
Reviewed-by: https://github.com/awesomekling

Userland/Libraries/LibWeb/HTML/HTMLFormElement.cpp

@@ -888,7 +888,7 @@ void HTMLFormElement::plan_to_navigate_to(URL::URL url, Variant<Empty, String, P
     // NOTE: `this`, `actual_resource` and `target_navigable` are protected by JS::SafeFunction.
     queue_an_element_task(Task::Source::DOMManipulation, [this, url, post_resource, target_navigable, history_handling, referrer_policy, user_involvement]() {
         // 1. Set the form's planned navigation to null.
-        m_planned_navigation = nullptr;
+        m_planned_navigation = {};
 
         // 2. Navigate targetNavigable to url using the form element's node document, with historyHandling set to historyHandling,
         //    referrerPolicy set to referrerPolicy, documentResource set to postResource, and cspNavigationType set to "form-submission".

Userland/Libraries/LibWeb/HTML/HTMLFormElement.h

@@ -142,7 +142,7 @@ private:
     // https://html.spec.whatwg.org/multipage/form-control-infrastructure.html#planned-navigation
     // Each form element has a planned navigation, which is either null or a task; when the form is first created,
     // its planned navigation must be set to null.
-    Task const* m_planned_navigation { nullptr };
+    JS::GCPtr<Task const> m_planned_navigation;
 };
 
 }

Userland/Libraries/LibWeb/HTML/Scripting/TemporaryExecutionContext.cpp

@@ -13,16 +13,16 @@ TemporaryExecutionContext::TemporaryExecutionContext(EnvironmentSettingsObject&
     : m_environment_settings(environment_settings)
     , m_callbacks_enabled(callbacks_enabled)
 {
-    m_environment_settings.prepare_to_run_script();
+    m_environment_settings->prepare_to_run_script();
     if (m_callbacks_enabled == CallbacksEnabled::Yes)
-        m_environment_settings.prepare_to_run_callback();
+        m_environment_settings->prepare_to_run_callback();
 }
 
 TemporaryExecutionContext::~TemporaryExecutionContext()
 {
-    m_environment_settings.clean_up_after_running_script();
+    m_environment_settings->clean_up_after_running_script();
     if (m_callbacks_enabled == CallbacksEnabled::Yes)
-        m_environment_settings.clean_up_after_running_callback();
+        m_environment_settings->clean_up_after_running_callback();
 }
 
 }

Userland/Libraries/LibWeb/HTML/Scripting/TemporaryExecutionContext.h

@@ -24,7 +24,7 @@ public:
     ~TemporaryExecutionContext();
 
 private:
-    EnvironmentSettingsObject& m_environment_settings;
+    JS::NonnullGCPtr<EnvironmentSettingsObject> m_environment_settings;
     CallbacksEnabled m_callbacks_enabled { CallbacksEnabled::No };
 };