LibJS+Everywhere: Allow Cell::initialize overrides to throw OOM errors

Note that as of this commit, there aren't any such throwers, and the
call site in Heap::allocate will drop exceptions on the floor. This
commit only serves to change the declaration of the overrides, make sure
they return an empty value, and to propagate OOM errors frm their base
initialize invocations.

Userland/Libraries/LibWeb/UIEvents/FocusEvent.cpp

@@ -22,10 +22,12 @@ FocusEvent::FocusEvent(JS::Realm& realm, DeprecatedFlyString const& event_name,
 
 FocusEvent::~FocusEvent() = default;
 
-void FocusEvent::initialize(JS::Realm& realm)
+JS::ThrowCompletionOr<void> FocusEvent::initialize(JS::Realm& realm)
 {
-    Base::initialize(realm);
+    MUST_OR_THROW_OOM(Base::initialize(realm));
     set_prototype(&Bindings::ensure_web_prototype<Bindings::FocusEventPrototype>(realm, "FocusEvent"));
+
+    return {};
 }
 
 }

Userland/Libraries/LibWeb/UIEvents/FocusEvent.h

@@ -25,7 +25,7 @@ public:
 private:
     FocusEvent(JS::Realm&, DeprecatedFlyString const& event_name, FocusEventInit const&);
 
-    virtual void initialize(JS::Realm&) override;
+    virtual JS::ThrowCompletionOr<void> initialize(JS::Realm&) override;
 };
 
 }

Userland/Libraries/LibWeb/UIEvents/KeyboardEvent.cpp

@@ -132,10 +132,12 @@ KeyboardEvent::KeyboardEvent(JS::Realm& realm, DeprecatedFlyString const& event_
 
 KeyboardEvent::~KeyboardEvent() = default;
 
-void KeyboardEvent::initialize(JS::Realm& realm)
+JS::ThrowCompletionOr<void> KeyboardEvent::initialize(JS::Realm& realm)
 {
-    Base::initialize(realm);
+    MUST_OR_THROW_OOM(Base::initialize(realm));
     set_prototype(&Bindings::ensure_web_prototype<Bindings::KeyboardEventPrototype>(realm, "KeyboardEvent"));
+
+    return {};
 }
 
 }

Userland/Libraries/LibWeb/UIEvents/KeyboardEvent.h

@@ -56,7 +56,7 @@ public:
 private:
     KeyboardEvent(JS::Realm&, DeprecatedFlyString const& event_name, KeyboardEventInit const& event_init);
 
-    virtual void initialize(JS::Realm&) override;
+    virtual JS::ThrowCompletionOr<void> initialize(JS::Realm&) override;
 
     DeprecatedString m_key;
     DeprecatedString m_code;

Userland/Libraries/LibWeb/UIEvents/MouseEvent.cpp

@@ -29,10 +29,12 @@ MouseEvent::MouseEvent(JS::Realm& realm, DeprecatedFlyString const& event_name,
 
 MouseEvent::~MouseEvent() = default;
 
-void MouseEvent::initialize(JS::Realm& realm)
+JS::ThrowCompletionOr<void> MouseEvent::initialize(JS::Realm& realm)
 {
-    Base::initialize(realm);
+    MUST_OR_THROW_OOM(Base::initialize(realm));
     set_prototype(&Bindings::ensure_web_prototype<Bindings::MouseEventPrototype>(realm, "MouseEvent"));
+
+    return {};
 }
 
 // https://www.w3.org/TR/uievents/#dom-mouseevent-button

Userland/Libraries/LibWeb/UIEvents/MouseEvent.h

@@ -58,7 +58,7 @@ public:
 protected:
     MouseEvent(JS::Realm&, DeprecatedFlyString const& event_name, MouseEventInit const& event_init);
 
-    virtual void initialize(JS::Realm&) override;
+    virtual JS::ThrowCompletionOr<void> initialize(JS::Realm&) override;
 
 private:
     void set_event_characteristics();

Userland/Libraries/LibWeb/UIEvents/UIEvent.cpp

@@ -33,10 +33,12 @@ UIEvent::UIEvent(JS::Realm& realm, DeprecatedFlyString const& event_name, UIEven
 
 UIEvent::~UIEvent() = default;
 
-void UIEvent::initialize(JS::Realm& realm)
+JS::ThrowCompletionOr<void> UIEvent::initialize(JS::Realm& realm)
 {
-    Base::initialize(realm);
+    MUST_OR_THROW_OOM(Base::initialize(realm));
     set_prototype(&Bindings::ensure_web_prototype<Bindings::UIEventPrototype>(realm, "UIEvent"));
+
+    return {};
 }
 
 void UIEvent::visit_edges(Cell::Visitor& visitor)

Userland/Libraries/LibWeb/UIEvents/UIEvent.h

@@ -41,7 +41,7 @@ protected:
     UIEvent(JS::Realm&, DeprecatedFlyString const& event_name);
     UIEvent(JS::Realm&, DeprecatedFlyString const& event_name, UIEventInit const& event_init);
 
-    virtual void initialize(JS::Realm&) override;
+    virtual JS::ThrowCompletionOr<void> initialize(JS::Realm&) override;
     virtual void visit_edges(Cell::Visitor&) override;
 
     JS::GCPtr<HTML::Window> m_view;

Userland/Libraries/LibWeb/UIEvents/WheelEvent.cpp

@@ -22,10 +22,12 @@ WheelEvent::WheelEvent(JS::Realm& realm, DeprecatedFlyString const& event_name,
 
 WheelEvent::~WheelEvent() = default;
 
-void WheelEvent::initialize(JS::Realm& realm)
+JS::ThrowCompletionOr<void> WheelEvent::initialize(JS::Realm& realm)
 {
-    Base::initialize(realm);
+    MUST_OR_THROW_OOM(Base::initialize(realm));
     set_prototype(&Bindings::ensure_web_prototype<Bindings::WheelEventPrototype>(realm, "WheelEvent"));
+
+    return {};
 }
 
 WheelEvent* WheelEvent::create(JS::Realm& realm, DeprecatedFlyString const& event_name, WheelEventInit const& event_init)

Userland/Libraries/LibWeb/UIEvents/WheelEvent.h

@@ -42,7 +42,7 @@ public:
 private:
     WheelEvent(JS::Realm&, DeprecatedFlyString const& event_name, WheelEventInit const& event_init);
 
-    virtual void initialize(JS::Realm&) override;
+    virtual JS::ThrowCompletionOr<void> initialize(JS::Realm&) override;
 
     void set_event_characteristics();