LibWeb+LibJS: Make the EventTarget hierarchy (incl. DOM) GC-allocated

This is a monster patch that turns all EventTargets into GC-allocated
PlatformObjects. Their C++ wrapper classes are removed, and the LibJS
garbage collector is now responsible for their lifetimes.

There's a fair amount of hacks and band-aids in this patch, and we'll
have a lot of cleanup to do after this.

Userland/Libraries/LibWeb/HTML/EventLoop/EventLoop.cpp

@@ -141,12 +141,12 @@ void EventLoop::process()
     //               - Any Document B whose browsing context's container document is A must be listed after A in the list.
     //               - If there are two documents A and B whose browsing contexts are both child browsing contexts whose container documents are another Document C, then the order of A and B in the list must match the shadow-including tree order of their respective browsing context containers in C's node tree.
     // FIXME: NOTE: The sort order specified above is missing here!
-    NonnullRefPtrVector<DOM::Document> docs = documents_in_this_event_loop();
+    Vector<JS::Handle<DOM::Document>> docs = documents_in_this_event_loop();
 
     auto for_each_fully_active_document_in_docs = [&](auto&& callback) {
         for (auto& document : docs) {
-            if (document.is_fully_active())
-                callback(document);
+            if (document->is_fully_active())
+                callback(*document);
         }
     };
 
@@ -215,7 +215,7 @@ void EventLoop::process()
         // 3. For each win of the same-loop windows for this event loop,
         //    perform the start an idle period algorithm for win with computeDeadline. [REQUESTIDLECALLBACK]
         for (auto& win : same_loop_windows())
-            win.start_an_idle_period();
+            win->start_an_idle_period();
     }
 
     // FIXME: 14. If this is a worker event loop, then:
@@ -248,8 +248,8 @@ void queue_global_task(HTML::Task::Source source, JS::Object& global_object, Fun
 
     // 2. Let document be global's associated Document, if global is a Window object; otherwise null.
     DOM::Document* document { nullptr };
-    if (is<Bindings::WindowObject>(global_object)) {
-        auto& window_object = verify_cast<Bindings::WindowObject>(global_object);
+    if (is<HTML::Window>(global_object)) {
+        auto& window_object = verify_cast<HTML::Window>(global_object);
         document = &window_object.impl().associated_document();
     }
 
@@ -320,12 +320,12 @@ void EventLoop::perform_a_microtask_checkpoint()
     m_performing_a_microtask_checkpoint = false;
 }
 
-NonnullRefPtrVector<DOM::Document> EventLoop::documents_in_this_event_loop() const
+Vector<JS::Handle<DOM::Document>> EventLoop::documents_in_this_event_loop() const
 {
-    NonnullRefPtrVector<DOM::Document> documents;
+    Vector<JS::Handle<DOM::Document>> documents;
     for (auto& document : m_documents) {
         VERIFY(document);
-        documents.append(*document);
+        documents.append(JS::make_handle(*document.ptr()));
     }
     return documents;
 }
@@ -368,11 +368,11 @@ void EventLoop::unregister_environment_settings_object(Badge<EnvironmentSettings
 }
 
 // https://html.spec.whatwg.org/multipage/webappapis.html#same-loop-windows
-NonnullRefPtrVector<Window> EventLoop::same_loop_windows() const
+Vector<JS::Handle<HTML::Window>> EventLoop::same_loop_windows() const
 {
-    NonnullRefPtrVector<Window> windows;
+    Vector<JS::Handle<HTML::Window>> windows;
     for (auto& document : documents_in_this_event_loop())
-        windows.append(document.window());
+        windows.append(JS::make_handle(document->window()));
     return windows;
 }
 
@@ -394,7 +394,7 @@ double EventLoop::compute_deadline() const
         // 1. If windowInSameLoop's map of animation frame callbacks is not empty,
         //    or if the user agent believes that the windowInSameLoop might have pending rendering updates,
         //    set hasPendingRenders to true.
-        if (window.has_animation_frame_callbacks())
+        if (window->has_animation_frame_callbacks())
             has_pending_renders = true;
         // FIXME: 2. Let timerCallbackEstimates be the result of getting the values of windowInSameLoop's map of active timers.
         // FIXME: 3. For each timeoutDeadline of timerCallbackEstimates, if timeoutDeadline is less than deadline, set deadline to timeoutDeadline.

Userland/Libraries/LibWeb/HTML/EventLoop/EventLoop.h

@@ -53,9 +53,9 @@ public:
     void register_document(Badge<DOM::Document>, DOM::Document&);
     void unregister_document(Badge<DOM::Document>, DOM::Document&);
 
-    NonnullRefPtrVector<DOM::Document> documents_in_this_event_loop() const;
+    Vector<JS::Handle<DOM::Document>> documents_in_this_event_loop() const;
 
-    NonnullRefPtrVector<Window> same_loop_windows() const;
+    Vector<JS::Handle<HTML::Window>> same_loop_windows() const;
 
     void push_onto_backup_incumbent_settings_object_stack(Badge<EnvironmentSettingsObject>, EnvironmentSettingsObject& environment_settings_object);
     void pop_backup_incumbent_settings_object_stack(Badge<EnvironmentSettingsObject>);

Userland/Libraries/LibWeb/HTML/EventLoop/Task.cpp

@@ -12,7 +12,7 @@ namespace Web::HTML {
 Task::Task(Source source, DOM::Document* document, Function<void()> steps)
     : m_source(source)
     , m_steps(move(steps))
-    , m_document(document)
+    , m_document(JS::make_handle(document))
 {
 }
 
@@ -27,7 +27,17 @@ void Task::execute()
 bool Task::is_runnable() const
 {
     // A task is runnable if its document is either null or fully active.
-    return !m_document || m_document->is_fully_active();
+    return !m_document.ptr() || m_document->is_fully_active();
+}
+
+DOM::Document* Task::document()
+{
+    return m_document.ptr();
+}
+
+DOM::Document const* Task::document() const
+{
+    return m_document.ptr();
 }
 
 }

Userland/Libraries/LibWeb/HTML/EventLoop/Task.h

@@ -9,6 +9,7 @@
 #include <AK/Function.h>
 #include <AK/NonnullOwnPtr.h>
 #include <AK/RefPtr.h>
+#include <LibJS/Heap/Handle.h>
 #include <LibWeb/Forward.h>
 
 namespace Web::HTML {
@@ -38,8 +39,8 @@ public:
     Source source() const { return m_source; }
     void execute();
 
-    DOM::Document* document() { return m_document; }
-    DOM::Document const* document() const { return m_document; }
+    DOM::Document* document();
+    DOM::Document const* document() const;
 
     bool is_runnable() const;
 
@@ -48,7 +49,7 @@ private:
 
     Source m_source { Source::Unspecified };
     Function<void()> m_steps;
-    RefPtr<DOM::Document> m_document;
+    JS::Handle<DOM::Document> m_document;
 };
 
 }