When V8 called back DOM operations of global objects in Blink, v8::FunctionCallbackInfo::Holder() points to the global proxy object, not the global object.  There is no way to determine if Holder() is the global proxy object or global object, so it's difficult to extract an internal field from the global object.

We'd like the global proxy object to proxy the call to GetInternalField(index) to the underlying global object so that Holder()->GetInternalField(index) works even when Holder() is the global proxy object.