Revert the commits adding new GC-related APIs.

We need to solve efficiency problems first.

This reverts the following revisions: 14283 14286 14221 14215

BUG=

Review URL: https://codereview.chromium.org/14294009

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

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@14293 ce2b1a6d-e550-0410-aec6-3dcde31c8c00