LibWeb: Move Web prototypes and constructors to new Intrinsics object

This Intrinsics object hangs off of a new HostDefined struct that takes
the place of EnvironmentSettingsObject as the true [[HostDefined]] slot
on JS::Realm objects created by LibWeb.

This gets the intrinsics off of the GlobalObject, Window, similar to the
previous refactor of LibJS to move the intrinsics into the Realm's
[[Intrinics]] internal slot.

A side effect of this change is that we cannot fully initialize a Window
object until the [[HostDefined]] slot has been installed into the realm,
which happens with the creation of the WindowEnvironmentSettingsObject.

As such, any Window usage that has not been funned through a WindowESO
will not have any cached Web prototyped or constructors, and will not
have Window APIs available to javascript code. Currently this seems
limited to usage of Window in the CSS parser, but a subsequent commit
will clean those up to take Realm as well. However, this commit compiles
so let's cut it off here :^).

Userland/Libraries/LibWeb/Bindings/HostDefined.cpp

@@ -0,0 +1,22 @@
+/*
+ * Copyright (c) 2022, Andrew Kaster <akaster@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibJS/Heap/Cell.h>
+#include <LibJS/Runtime/Realm.h>
+#include <LibWeb/Bindings/HostDefined.h>
+#include <LibWeb/Bindings/Intrinsics.h>
+#include <LibWeb/HTML/Scripting/Environments.h>
+
+namespace Web::Bindings {
+
+void HostDefined::visit_edges(JS::Cell::Visitor& visitor)
+{
+    JS::Realm::HostDefined::visit_edges(visitor);
+    visitor.visit(environment_settings_object);
+    visitor.visit(*intrinsics);
+}
+
+}

Userland/Libraries/LibWeb/Bindings/HostDefined.h

@@ -0,0 +1,35 @@
+/*
+ * Copyright (c) 2022, Andrew Kaster <akaster@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/TypeCasts.h>
+#include <LibJS/Heap/GCPtr.h>
+#include <LibJS/Runtime/Realm.h>
+#include <LibWeb/Forward.h>
+
+namespace Web::Bindings {
+
+struct HostDefined : public JS::Realm::HostDefined {
+    HostDefined(JS::GCPtr<HTML::EnvironmentSettingsObject> eso, JS::NonnullGCPtr<Intrinsics> intrinsics)
+        : environment_settings_object(eso)
+        , intrinsics(intrinsics)
+    {
+    }
+    virtual ~HostDefined() override = default;
+    virtual void visit_edges(JS::Cell::Visitor& visitor) override;
+
+    // NOTE: Only the root execution environment in the main thread VM ever sets this to nullptr
+    JS::GCPtr<HTML::EnvironmentSettingsObject> environment_settings_object;
+    JS::NonnullGCPtr<Intrinsics> intrinsics;
+};
+
+inline HTML::EnvironmentSettingsObject& host_defined_environment_settings_object(JS::Realm& realm)
+{
+    return *verify_cast<HostDefined>(realm.host_defined())->environment_settings_object;
+}
+
+}

Userland/Libraries/LibWeb/Bindings/Intrinsics.cpp

@@ -0,0 +1,36 @@
+/*
+ * Copyright (c) 2022, Andrew Kaster <akaster@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <AK/HashMap.h>
+#include <AK/String.h>
+#include <LibJS/Forward.h>
+#include <LibJS/Runtime/NativeFunction.h>
+#include <LibJS/Runtime/Object.h>
+#include <LibWeb/Bindings/Intrinsics.h>
+
+namespace Web::Bindings {
+
+JS::Object& Intrinsics::cached_web_prototype(String const& class_name)
+{
+    auto it = m_prototypes.find(class_name);
+    if (it == m_prototypes.end()) {
+        dbgln("Missing prototype: {}", class_name);
+    }
+    VERIFY(it != m_prototypes.end());
+    return *it->value;
+}
+
+void Intrinsics::visit_edges(JS::Cell::Visitor& visitor)
+{
+    Base::visit_edges(visitor);
+
+    for (auto& it : m_prototypes)
+        visitor.visit(it.value);
+    for (auto& it : m_constructors)
+        visitor.visit(it.value);
+}
+
+}

Userland/Libraries/LibWeb/Bindings/Intrinsics.h

@@ -0,0 +1,85 @@
+/*
+ * Copyright (c) 2022, Andrew Kaster <akaster@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/Forward.h>
+#include <AK/HashMap.h>
+#include <LibJS/Forward.h>
+#include <LibJS/Heap/Cell.h>
+#include <LibJS/Heap/Heap.h>
+#include <LibJS/Runtime/VM.h>
+#include <LibWeb/Bindings/HostDefined.h>
+
+namespace Web::Bindings {
+
+class Intrinsics final : public JS::Cell {
+    JS_CELL(Intrinsics, JS::Cell);
+
+public:
+    Intrinsics(JS::Realm& realm)
+        : m_realm(realm)
+    {
+    }
+
+    JS::Object& cached_web_prototype(String const& class_name);
+
+    template<typename T>
+    JS::Object& ensure_web_prototype(String const& class_name)
+    {
+        auto it = m_prototypes.find(class_name);
+        if (it != m_prototypes.end())
+            return *it->value;
+        auto& realm = *m_realm;
+        auto* prototype = heap().allocate<T>(realm, realm);
+        m_prototypes.set(class_name, prototype);
+        return *prototype;
+    }
+
+    template<typename T>
+    JS::NativeFunction& ensure_web_constructor(String const& class_name)
+    {
+        auto it = m_constructors.find(class_name);
+        if (it != m_constructors.end())
+            return *it->value;
+        auto& realm = *m_realm;
+        auto* constructor = heap().allocate<T>(realm, realm);
+        m_constructors.set(class_name, constructor);
+        return *constructor;
+    }
+
+private:
+    virtual void visit_edges(JS::Cell::Visitor&) override;
+
+    HashMap<String, JS::Object*> m_prototypes;
+    HashMap<String, JS::NativeFunction*> m_constructors;
+
+    JS::NonnullGCPtr<JS::Realm> m_realm;
+};
+
+inline Intrinsics& host_defined_intrinsics(JS::Realm& realm)
+{
+    return *verify_cast<HostDefined>(realm.host_defined())->intrinsics;
+}
+
+template<typename T>
+JS::Object& ensure_web_prototype(JS::Realm& realm, String const& class_name)
+{
+    return host_defined_intrinsics(realm).ensure_web_prototype<T>(class_name);
+}
+
+template<typename T>
+JS::NativeFunction& ensure_web_constructor(JS::Realm& realm, String const& class_name)
+{
+    return host_defined_intrinsics(realm).ensure_web_constructor<T>(class_name);
+}
+
+inline JS::Object& cached_web_prototype(JS::Realm& realm, String const& class_name)
+{
+    return host_defined_intrinsics(realm).cached_web_prototype(class_name);
+}
+
+}

Userland/Libraries/LibWeb/Bindings/MainThreadVM.cpp

@@ -11,6 +11,7 @@
 #include <LibJS/Runtime/FinalizationRegistry.h>
 #include <LibJS/Runtime/NativeFunction.h>
 #include <LibJS/Runtime/VM.h>
+#include <LibWeb/Bindings/Intrinsics.h>
 #include <LibWeb/Bindings/LocationObject.h>
 #include <LibWeb/Bindings/MainThreadVM.h>
 #include <LibWeb/DOM/Document.h>
@@ -181,7 +182,7 @@ JS::VM& main_thread_vm()
             // 2. Queue a global task on the JavaScript engine task source given global to perform the following steps:
             HTML::queue_global_task(HTML::Task::Source::JavaScriptEngine, global, [&finalization_registry]() mutable {
                 // 1. Let entry be finalizationRegistry.[[CleanupCallback]].[[Callback]].[[Realm]]'s environment settings object.
-                auto& entry = verify_cast<HTML::EnvironmentSettingsObject>(*finalization_registry.cleanup_callback().callback.cell()->realm()->host_defined());
+                auto& entry = host_defined_environment_settings_object(*finalization_registry.cleanup_callback().callback.cell()->realm());
 
                 // 2. Check if we can run script with entry. If this returns "do not run", then return.
                 if (entry.can_run_script() == HTML::RunScriptDecision::DoNotRun)
@@ -207,7 +208,7 @@ JS::VM& main_thread_vm()
             // 1. If realm is not null, then let job settings be the settings object for realm. Otherwise, let job settings be null.
             HTML::EnvironmentSettingsObject* job_settings { nullptr };
             if (realm)
-                job_settings = verify_cast<HTML::EnvironmentSettingsObject>(realm->host_defined());
+                job_settings = &host_defined_environment_settings_object(*realm);
 
             // IMPLEMENTATION DEFINED: The JS spec says we must take implementation defined steps to make the currently active script or module at the time of HostEnqueuePromiseJob being invoked
             //                         also be the active script or module of the job at the time of its invocation.
@@ -312,6 +313,11 @@ JS::VM& main_thread_vm()
             },
             nullptr));
 
+        auto* root_realm = custom_data.root_execution_context->realm;
+        auto* intrinsics = root_realm->heap().allocate<Intrinsics>(*root_realm, *root_realm);
+        auto host_defined = make<HostDefined>(nullptr, *intrinsics);
+        root_realm->set_host_defined(move(host_defined));
+
         vm->push_execution_context(*custom_data.root_execution_context);
     }
     return *vm;

Userland/Libraries/LibWeb/Bindings/WindowObjectHelper.h

@@ -394,8 +394,9 @@
 
 #define ADD_WINDOW_OBJECT_CONSTRUCTOR_AND_PROTOTYPE(interface_name, constructor_name, prototype_name)                                \
     {                                                                                                                                \
-        auto& prototype = ensure_web_prototype<Bindings::prototype_name>(#interface_name);                                           \
-        auto& constructor = ensure_web_constructor<Bindings::constructor_name>(#interface_name);                                     \
+        auto& prototype = Bindings::ensure_web_prototype<Bindings::prototype_name>(realm, #interface_name);                          \
+        auto& constructor = Bindings::ensure_web_constructor<Bindings::constructor_name>(realm, #interface_name);                    \
+        define_direct_property(#interface_name, &constructor, JS::Attribute::Writable | JS::Attribute::Configurable);                \
         prototype.define_direct_property(vm.names.constructor, &constructor, JS::Attribute::Writable | JS::Attribute::Configurable); \
         constructor.define_direct_property(vm.names.name, js_string(vm, #interface_name), JS::Attribute::Configurable);              \
     }
@@ -405,6 +406,7 @@
 
 #define ADD_WINDOW_OBJECT_INTERFACES                                                                \
     auto& vm = this->vm();                                                                          \
+    auto& realm = this->realm();                                                                    \
     ADD_WINDOW_OBJECT_INTERFACE(AbortController)                                                    \
     ADD_WINDOW_OBJECT_INTERFACE(AbortSignal)                                                        \
     ADD_WINDOW_OBJECT_INTERFACE(AbstractRange)                                                      \

Userland/Libraries/LibWeb/CMakeLists.txt

@@ -3,7 +3,9 @@ include(libweb_generators)
 set(SOURCES
     Bindings/AudioConstructor.cpp
     Bindings/CSSNamespace.cpp
+    Bindings/HostDefined.cpp
     Bindings/ImageConstructor.cpp
+    Bindings/Intrinsics.cpp
     Bindings/LegacyPlatformObject.cpp
     Bindings/LocationConstructor.cpp
     Bindings/LocationObject.cpp

Userland/Libraries/LibWeb/DOM/Document.cpp

@@ -1087,7 +1087,7 @@ Color Document::visited_link_color() const
 HTML::EnvironmentSettingsObject& Document::relevant_settings_object()
 {
     // Then, the relevant settings object for a platform object o is the environment settings object of the relevant Realm for o.
-    return verify_cast<HTML::EnvironmentSettingsObject>(*realm().host_defined());
+    return Bindings::host_defined_environment_settings_object(realm());
 }
 
 JS::Value Document::run_javascript(StringView source, StringView filename)

Userland/Libraries/LibWeb/DOM/EventTarget.cpp

@@ -556,7 +556,7 @@ void EventTarget::activate_event_handler(FlyString const& name, HTML::EventHandl
         0, "", &realm);
 
     // NOTE: As per the spec, the callback context is arbitrary.
-    auto* callback = realm.heap().allocate_without_realm<WebIDL::CallbackType>(*callback_function, verify_cast<HTML::EnvironmentSettingsObject>(*realm.host_defined()));
+    auto* callback = realm.heap().allocate_without_realm<WebIDL::CallbackType>(*callback_function, Bindings::host_defined_environment_settings_object(realm));
 
     // 5. Let listener be a new event listener whose type is the event handler event type corresponding to eventHandler and callback is callback.
     auto* listener = realm.heap().allocate_without_realm<DOMEventListener>();

Userland/Libraries/LibWeb/Forward.h

@@ -473,6 +473,7 @@ class URLSearchParamsIterator;
 }
 
 namespace Web::Bindings {
+class Intrinsics;
 class LocationObject;
 class OptionConstructor;
 class RangePrototype;

Userland/Libraries/LibWeb/HTML/BrowsingContext.cpp

@@ -164,7 +164,7 @@ NonnullRefPtr<BrowsingContext> BrowsingContext::create_a_new_browsing_context(Pa
     auto load_timing_info = DOM::DocumentLoadTimingInfo();
     load_timing_info.navigation_start_time = HighResolutionTime::coarsen_time(
         unsafe_context_creation_time,
-        verify_cast<WindowEnvironmentSettingsObject>(window->realm().host_defined())->cross_origin_isolated_capability() == CanUseCrossOriginIsolatedAPIs::Yes);
+        verify_cast<WindowEnvironmentSettingsObject>(Bindings::host_defined_environment_settings_object(window->realm())).cross_origin_isolated_capability() == CanUseCrossOriginIsolatedAPIs::Yes);
 
     // 13. Let coop be a new cross-origin opener policy.
     auto coop = CrossOriginOpenerPolicy {};

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

@@ -286,7 +286,7 @@ EnvironmentSettingsObject& incumbent_settings_object()
     }
 
     // 3. Return context's Realm component's settings object.
-    return verify_cast<EnvironmentSettingsObject>(*context->realm->host_defined());
+    return Bindings::host_defined_environment_settings_object(*context->realm);
 }
 
 // https://html.spec.whatwg.org/multipage/webappapis.html#concept-incumbent-realm
@@ -310,7 +310,7 @@ EnvironmentSettingsObject& current_settings_object()
     auto& vm = event_loop.vm();
 
     // Then, the current settings object is the environment settings object of the current Realm Record.
-    return verify_cast<EnvironmentSettingsObject>(*vm.current_realm()->host_defined());
+    return Bindings::host_defined_environment_settings_object(*vm.current_realm());
 }
 
 // https://html.spec.whatwg.org/multipage/webappapis.html#current-global-object
@@ -334,7 +334,7 @@ JS::Realm& relevant_realm(JS::Object const& object)
 EnvironmentSettingsObject& relevant_settings_object(JS::Object const& object)
 {
     // Then, the relevant settings object for a platform object o is the environment settings object of the relevant Realm for o.
-    return verify_cast<EnvironmentSettingsObject>(*relevant_realm(object).host_defined());
+    return Bindings::host_defined_environment_settings_object(relevant_realm(object));
 }
 
 EnvironmentSettingsObject& relevant_settings_object(DOM::Node const& node)

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

@@ -54,7 +54,9 @@ enum class RunScriptDecision {
 // https://html.spec.whatwg.org/multipage/webappapis.html#environment-settings-object
 struct EnvironmentSettingsObject
     : public Environment
-    , public JS::Realm::HostDefined {
+    , public JS::Cell {
+    JS_CELL(EnvironmentSettingsObject, JS::Cell);
+
     virtual ~EnvironmentSettingsObject() override;
 
     // https://html.spec.whatwg.org/multipage/webappapis.html#concept-environment-target-browsing-context

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

@@ -4,6 +4,8 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
+#include <LibWeb/Bindings/HostDefined.h>
+#include <LibWeb/Bindings/Intrinsics.h>
 #include <LibWeb/DOM/Document.h>
 #include <LibWeb/HTML/Scripting/WindowEnvironmentSettingsObject.h>
 #include <LibWeb/HTML/Window.h>
@@ -36,7 +38,7 @@ void WindowEnvironmentSettingsObject::setup(AK::URL const& creation_url, Nonnull
 
     // 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, move(execution_context)));
+    auto* settings_object = realm->heap().allocate<WindowEnvironmentSettingsObject>(*realm, window, move(execution_context));
 
     // 4. If reservedEnvironment is non-null, then:
     if (reserved_environment.has_value()) {
@@ -68,7 +70,14 @@ void WindowEnvironmentSettingsObject::setup(AK::URL const& creation_url, Nonnull
     settings_object->top_level_origin = top_level_origin;
 
     // 7. Set realm's [[HostDefined]] field to settings object.
-    realm->set_host_defined(move(settings_object));
+    // Non-Standard: We store the ESO next to the web intrinsics in a custom HostDefined object
+    auto* intrinsics = realm->heap().allocate<Bindings::Intrinsics>(*realm, *realm);
+    auto host_defined = make<Bindings::HostDefined>(*settings_object, *intrinsics);
+    realm->set_host_defined(move(host_defined));
+
+    // Non-Standard: We cannot fully initialize window object until *after* the we set up
+    //    the realm's [[HostDefined]] internal slot as the internal slot contains the web platform intrinsics
+    window.initialize_web_interfaces({});
 }
 
 // https://html.spec.whatwg.org/multipage/window-object.html#script-settings-for-window-objects:responsible-document

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

@@ -12,6 +12,8 @@
 namespace Web::HTML {
 
 class WindowEnvironmentSettingsObject final : public EnvironmentSettingsObject {
+    JS_CELL(WindowEnvironmentSettingsObject, EnvironmentSettingsObject);
+
 public:
     static void setup(AK::URL const& creation_url, NonnullOwnPtr<JS::ExecutionContext>, Optional<Environment>, AK::URL top_level_creation_url, Origin top_level_origin);
 

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

@@ -13,23 +13,27 @@
 namespace Web::HTML {
 
 class WorkerEnvironmentSettingsObject final
-    : public EnvironmentSettingsObject
-    , public Weakable<WorkerEnvironmentSettingsObject> {
+    : public EnvironmentSettingsObject {
+    JS_CELL(WindowEnvironmentSettingsObject, EnvironmentSettingsObject);
+
 public:
     WorkerEnvironmentSettingsObject(NonnullOwnPtr<JS::ExecutionContext> execution_context)
         : EnvironmentSettingsObject(move(execution_context))
     {
     }
 
-    static WeakPtr<WorkerEnvironmentSettingsObject> setup(NonnullOwnPtr<JS::ExecutionContext> execution_context /* FIXME: null or an environment reservedEnvironment, a URL topLevelCreationURL, and an origin topLevelOrigin */)
+    static JS::NonnullGCPtr<WorkerEnvironmentSettingsObject> setup(NonnullOwnPtr<JS::ExecutionContext> execution_context /* FIXME: null or an environment reservedEnvironment, a URL topLevelCreationURL, and an origin topLevelOrigin */)
     {
         auto* realm = execution_context->realm;
         VERIFY(realm);
-        auto settings_object = adopt_own(*new WorkerEnvironmentSettingsObject(move(execution_context)));
+        auto settings_object = realm->heap().allocate<WorkerEnvironmentSettingsObject>(*realm, move(execution_context));
         settings_object->target_browsing_context = nullptr;
-        realm->set_host_defined(move(settings_object));
 
-        return static_cast<WorkerEnvironmentSettingsObject*>(realm->host_defined());
+        auto* intrinsics = realm->heap().allocate<Bindings::Intrinsics>(*realm, *realm);
+        auto host_defined = make<Bindings::HostDefined>(*settings_object, *intrinsics);
+        realm->set_host_defined(move(host_defined));
+
+        return *settings_object;
     }
 
     virtual ~WorkerEnvironmentSettingsObject() override = default;

Userland/Libraries/LibWeb/HTML/Window.cpp

@@ -96,26 +96,12 @@ void Window::visit_edges(JS::Cell::Visitor& visitor)
     visitor.visit(m_screen.ptr());
     visitor.visit(m_location_object);
     visitor.visit(m_crypto);
-    for (auto& it : m_prototypes)
-        visitor.visit(it.value);
-    for (auto& it : m_constructors)
-        visitor.visit(it.value);
     for (auto& it : m_timers)
         visitor.visit(it.value.ptr());
 }
 
 Window::~Window() = default;
 
-JS::Object& Window::cached_web_prototype(String const& class_name)
-{
-    auto it = m_prototypes.find(class_name);
-    if (it == m_prototypes.end()) {
-        dbgln("Missing prototype: {}", class_name);
-    }
-    VERIFY(it != m_prototypes.end());
-    return *it->value;
-}
-
 HighResolutionTime::Performance& Window::performance()
 {
     if (!m_performance)
@@ -750,7 +736,10 @@ void Window::initialize(JS::Realm& realm)
 
     // FIXME: This is a hack..
     realm.set_global_object(this, this);
+}
 
+void Window::initialize_web_interfaces(Badge<WindowEnvironmentSettingsObject>)
+{
     ADD_WINDOW_OBJECT_INTERFACES;
 
     Object::set_prototype(&ensure_web_prototype<Bindings::WindowPrototype>("Window"));

Userland/Libraries/LibWeb/HTML/Window.h

@@ -13,6 +13,7 @@
 #include <AK/TypeCasts.h>
 #include <AK/URL.h>
 #include <LibJS/Heap/Heap.h>
+#include <LibWeb/Bindings/Intrinsics.h>
 #include <LibWeb/DOM/EventTarget.h>
 #include <LibWeb/Forward.h>
 #include <LibWeb/HTML/AnimationFrameCallbackDriver.h>
@@ -123,6 +124,8 @@ public:
     // https://html.spec.whatwg.org/multipage/interaction.html#transient-activation
     bool has_transient_activation() const;
 
+    void initialize_web_interfaces(Badge<WindowEnvironmentSettingsObject>);
+
 private:
     explicit Window(JS::Realm&);
     virtual void initialize(JS::Realm&) override;
@@ -170,34 +173,18 @@ public:
     Bindings::LocationObject* location_object() { return m_location_object; }
     Bindings::LocationObject const* location_object() const { return m_location_object; }
 
-    JS::Object* web_prototype(String const& class_name) { return m_prototypes.get(class_name).value_or(nullptr); }
-    JS::NativeFunction* web_constructor(String const& class_name) { return m_constructors.get(class_name).value_or(nullptr); }
-
-    JS::Object& cached_web_prototype(String const& class_name);
+    JS::Object& cached_web_prototype(String const& class_name) { return Bindings::cached_web_prototype(realm(), class_name); }
 
     template<typename T>
     JS::Object& ensure_web_prototype(String const& class_name)
     {
-        auto it = m_prototypes.find(class_name);
-        if (it != m_prototypes.end())
-            return *it->value;
-        auto& realm = shape().realm();
-        auto* prototype = heap().allocate<T>(realm, realm);
-        m_prototypes.set(class_name, prototype);
-        return *prototype;
+        return Bindings::ensure_web_prototype<T>(realm(), class_name);
     }
 
     template<typename T>
     JS::NativeFunction& ensure_web_constructor(String const& class_name)
     {
-        auto it = m_constructors.find(class_name);
-        if (it != m_constructors.end())
-            return *it->value;
-        auto& realm = shape().realm();
-        auto* constructor = heap().allocate<T>(realm, realm);
-        m_constructors.set(class_name, constructor);
-        define_direct_property(class_name, JS::Value(constructor), JS::Attribute::Writable | JS::Attribute::Configurable);
-        return *constructor;
+        return Bindings::ensure_web_constructor<T>(realm(), class_name);
     }
 
     virtual JS::ThrowCompletionOr<bool> internal_set_prototype_of(JS::Object* prototype) override;
@@ -283,9 +270,6 @@ private:
 
     Bindings::LocationObject* m_location_object { nullptr };
 
-    HashMap<String, JS::Object*> m_prototypes;
-    HashMap<String, JS::NativeFunction*> m_constructors;
-
     // [[CrossOriginPropertyDescriptorMap]], https://html.spec.whatwg.org/multipage/browsers.html#crossoriginpropertydescriptormap
     CrossOriginPropertyDescriptorMap m_cross_origin_property_descriptor_map;
 };

Userland/Libraries/LibWeb/HTML/Worker.h

@@ -78,7 +78,7 @@ private:
 
     NonnullRefPtr<JS::VM> m_worker_vm;
     NonnullOwnPtr<JS::Interpreter> m_interpreter;
-    WeakPtr<WorkerEnvironmentSettingsObject> m_inner_settings;
+    JS::GCPtr<WorkerEnvironmentSettingsObject> m_inner_settings;
     JS::VM::InterpreterExecutionScope m_interpreter_scope;
     RefPtr<WorkerDebugConsoleClient> m_console;
 

Userland/Libraries/LibWeb/WebIDL/AbstractOperations.cpp

@@ -108,7 +108,7 @@ JS::Completion invoke_callback(WebIDL::CallbackType& callback, Optional<JS::Valu
     auto& realm = function_object.shape().realm();
 
     // 6. Let relevant settings be realm’s settings object.
-    auto& relevant_settings = verify_cast<HTML::EnvironmentSettingsObject>(*realm.host_defined());
+    auto& relevant_settings = Bindings::host_defined_environment_settings_object(realm);
 
     // 7. Let stored settings be value’s callback context.
     auto& stored_settings = callback.callback_context;

Userland/Libraries/LibWeb/WebIDL/AbstractOperations.h

@@ -11,6 +11,7 @@
 #include <LibJS/Forward.h>
 #include <LibJS/Runtime/AbstractOperations.h>
 #include <LibJS/Runtime/FunctionObject.h>
+#include <LibWeb/Bindings/HostDefined.h>
 #include <LibWeb/HTML/Scripting/Environments.h>
 #include <LibWeb/WebIDL/CallbackType.h>
 
@@ -60,7 +61,7 @@ JS::Completion call_user_object_operation(WebIDL::CallbackType& callback, String
     auto& realm = object.shape().realm();
 
     // 5. Let relevant settings be realm’s settings object.
-    auto& relevant_settings = verify_cast<HTML::EnvironmentSettingsObject>(*realm.host_defined());
+    auto& relevant_settings = Bindings::host_defined_environment_settings_object(realm);
 
     // 6. Let stored settings be value’s callback context.
     auto& stored_settings = callback.callback_context;

Userland/Services/WebContent/WebContentConsoleClient.cpp

@@ -29,7 +29,7 @@ WebContentConsoleClient::WebContentConsoleClient(JS::Console& console, JS::Realm
     auto console_global_object = realm.heap().allocate_without_realm<ConsoleGlobalObject>(realm, window);
 
     // NOTE: We need to push an execution context here for NativeFunction::create() to succeed during global object initialization.
-    auto& eso = verify_cast<Web::HTML::EnvironmentSettingsObject>(*realm.host_defined());
+    auto& eso = Web::Bindings::host_defined_environment_settings_object(realm);
     vm.push_execution_context(eso.realm_execution_context());
     console_global_object->initialize(realm);
     vm.pop_execution_context();
@@ -42,7 +42,7 @@ void WebContentConsoleClient::handle_input(String const& js_source)
     if (!m_realm)
         return;
 
-    auto& settings = verify_cast<Web::HTML::EnvironmentSettingsObject>(*m_realm->host_defined());
+    auto& settings = Web::Bindings::host_defined_environment_settings_object(*m_realm);
     auto script = Web::HTML::ClassicScript::create("(console)", js_source, settings, settings.api_base_url());
 
     // FIXME: Add parse error printouts back once ClassicScript can report parse errors.