[v8] Use v8::Object::WrapGlobal()

... for setting wrappable object on both JSGlobalProxy and its
hidden prototype (JSGlobalObject or remote object) instead of manual
approach requiring using of soon-to-be-deprecated
v8::Object::GetPrototype(). Basically we just move accesses of global
object's hidden prototype to V8 side without changing the logic.

This CL removes last usages of v8::Object::GetPrototype() without
changing behavior.

Bug: 333672197
Change-Id: I7548355c4ec0f5109c35be54dfde6f36575823c5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6650977
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Igor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1477761}