LibWeb: Move setting of Web object prototypes to initialize()

This needs to happen before prototype/constructor intitialization can be
made lazy. Otherwise, GC could run during the C++ constructor and try to
collect the object currently being created.

Userland/Libraries/LibWeb/UIEvents/WheelEvent.h

@@ -42,6 +42,8 @@ public:
 private:
     WheelEvent(JS::Realm&, DeprecatedFlyString const& event_name, WheelEventInit const& event_init);
 
+    virtual void initialize(JS::Realm&) override;
+
     void set_event_characteristics();
 
     double m_delta_x { 0 };