LibWeb: Put most LibWeb GC objects in type-specific heap blocks

With this change, we now have ~1200 CellAllocators across both LibJS and
LibWeb in a normal WebContent instance.

This gives us a minimum heap size of 4.7 MiB in the scenario where we
only have one cell allocated per type. Of course, in practice there will
be many more of each type, so the effective overhead is quite a bit
smaller than that in practice.

I left a few types unconverted to this mechanism because I got tired of
doing this. :^)

Userland/Libraries/LibWeb/XHR/FormData.cpp

@@ -15,6 +15,8 @@
 
 namespace Web::XHR {
 
+JS_DEFINE_ALLOCATOR(FormData);
+
 // https://xhr.spec.whatwg.org/#dom-formdata
 WebIDL::ExceptionOr<JS::NonnullGCPtr<FormData>> FormData::construct_impl(JS::Realm& realm, Optional<JS::NonnullGCPtr<HTML::HTMLFormElement>> form)
 {

Userland/Libraries/LibWeb/XHR/FormData.h

@@ -18,6 +18,7 @@ namespace Web::XHR {
 // https://xhr.spec.whatwg.org/#interface-formdata
 class FormData : public Bindings::PlatformObject {
     WEB_PLATFORM_OBJECT(FormData, Bindings::PlatformObject);
+    JS_DECLARE_ALLOCATOR(FormData);
 
 public:
     virtual ~FormData() override;

Userland/Libraries/LibWeb/XHR/FormDataIterator.cpp

@@ -23,6 +23,8 @@ void Intrinsics::create_web_prototype_and_constructor<FormDataIteratorPrototype>
 
 namespace Web::XHR {
 
+JS_DEFINE_ALLOCATOR(FormDataIterator);
+
 JS::NonnullGCPtr<FormDataIterator> FormDataIterator::create(FormData const& form_data, JS::Object::PropertyKind iterator_kind)
 {
     return form_data.heap().allocate<FormDataIterator>(form_data.realm(), form_data, iterator_kind);

Userland/Libraries/LibWeb/XHR/FormDataIterator.h

@@ -13,6 +13,7 @@ namespace Web::XHR {
 
 class FormDataIterator : public Bindings::PlatformObject {
     WEB_PLATFORM_OBJECT(FormDataIterator, Bindings::PlatformObject);
+    JS_DECLARE_ALLOCATOR(FormDataIterator);
 
 public:
     [[nodiscard]] static JS::NonnullGCPtr<FormDataIterator> create(FormData const&, JS::Object::PropertyKind iterator_kind);

Userland/Libraries/LibWeb/XHR/ProgressEvent.cpp

@@ -9,6 +9,8 @@
 
 namespace Web::XHR {
 
+JS_DEFINE_ALLOCATOR(ProgressEvent);
+
 JS::NonnullGCPtr<ProgressEvent> ProgressEvent::create(JS::Realm& realm, FlyString const& event_name, ProgressEventInit const& event_init)
 {
     return realm.heap().allocate<ProgressEvent>(realm, realm, event_name, event_init);

Userland/Libraries/LibWeb/XHR/ProgressEvent.h

@@ -22,6 +22,7 @@ struct ProgressEventInit : public DOM::EventInit {
 
 class ProgressEvent final : public DOM::Event {
     WEB_PLATFORM_OBJECT(ProgressEvent, DOM::Event);
+    JS_DECLARE_ALLOCATOR(ProgressEvent);
 
 public:
     [[nodiscard]] static JS::NonnullGCPtr<ProgressEvent> create(JS::Realm&, FlyString const& event_name, ProgressEventInit const& event_init);

Userland/Libraries/LibWeb/XHR/XMLHttpRequest.cpp

@@ -53,6 +53,8 @@
 
 namespace Web::XHR {
 
+JS_DEFINE_ALLOCATOR(XMLHttpRequest);
+
 WebIDL::ExceptionOr<JS::NonnullGCPtr<XMLHttpRequest>> XMLHttpRequest::construct_impl(JS::Realm& realm)
 {
     auto upload_object = realm.heap().allocate<XMLHttpRequestUpload>(realm, realm);

Userland/Libraries/LibWeb/XHR/XMLHttpRequest.h

@@ -30,6 +30,7 @@ using DocumentOrXMLHttpRequestBodyInit = Variant<JS::Handle<Web::DOM::Document>,
 
 class XMLHttpRequest final : public XMLHttpRequestEventTarget {
     WEB_PLATFORM_OBJECT(XMLHttpRequest, XMLHttpRequestEventTarget);
+    JS_DECLARE_ALLOCATOR(XMLHttpRequest);
 
 public:
     enum class State : u16 {

Userland/Libraries/LibWeb/XHR/XMLHttpRequestUpload.cpp

@@ -10,6 +10,8 @@
 
 namespace Web::XHR {
 
+JS_DEFINE_ALLOCATOR(XMLHttpRequestUpload);
+
 XMLHttpRequestUpload::XMLHttpRequestUpload(JS::Realm& realm)
     : XMLHttpRequestEventTarget(realm)
 {

Userland/Libraries/LibWeb/XHR/XMLHttpRequestUpload.h

@@ -12,6 +12,7 @@ namespace Web::XHR {
 
 class XMLHttpRequestUpload : public XMLHttpRequestEventTarget {
     WEB_PLATFORM_OBJECT(XMLHttpRequestUpload, XMLHttpRequestEventTarget);
+    JS_DECLARE_ALLOCATOR(XMLHttpRequestUpload);
 
 public:
     virtual ~XMLHttpRequestUpload() override;