V8HiddenPropertyName: Don't return Persistents by value.
V8HiddenPropertyName: Don't return Persistents by value.

This gets rid of more places where Persistent handles are copied
(see bug).

BUG=236290
R=dcarney@chromium.org

Review URL: https://codereview.chromium.org/16098004

git-svn-id: bf5cd6ccde378db821296732a091cfbcf5285fbd@151733 bbb929c8-8fbe-4397-9dbb-9b2b20218538

primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs