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/Geometry/DOMPointReadOnly.h

@@ -39,6 +39,8 @@ public:
 protected:
     DOMPointReadOnly(JS::Realm&, double x, double y, double z, double w);
 
+    virtual void initialize(JS::Realm&) override;
+
     double m_x;
     double m_y;
     double m_z;