Abort incremental marking in stress gc tests whenever we expect a full collection after executing CollectAllGarbage.

BUG=
R=mstarzinger@chromium.org

Review URL: https://codereview.chromium.org/17482003

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@15227 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Make isolate id getter public.

BUG=
R=svenpanne@chromium.org

Review URL: https://codereview.chromium.org/17343004

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@15228 ce2b1a6d-e550-0410-aec6-3dcde31c8c00