Transforming PersistentHandleVisitor to not need to copy Persistent handles.

This gets rid of more places where Persistent handles are copied
(see crbug.com/236290 ).

Transition plan: after this CL, Blink will be modified to work both with and
without the #define, then the #define will be removed from V8.

The corresponding Blink side changes are in https://codereview.chromium.org/15670010/ .

BUG=
R=dcarney@chromium.org, svenpanne@chromium.org

Review URL: https://codereview.chromium.org/15974006

Patch from Marja Hölttä <marja@chromium.org>.

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@14871 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Delete old GC related APIs.

Blink doesn't use them any more, and they have no other known users either.

BUG=
R=dcarney@chromium.org, svenpanne@chromium.org

Review URL: https://codereview.chromium.org/16124004

Patch from Marja Hölttä <marja@chromium.org>.

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@14872 ce2b1a6d-e550-0410-aec6-3dcde31c8c00