stub api getters

R=verwaest@chromium.org

BUG=

Review URL: https://codereview.chromium.org/150213003

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@18941 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Add global_context field to GlobalObject in heap profiler.

LOG=N
R=ulan@chromium.org, yurys@chromium.org

Review URL: https://codereview.chromium.org/143263015

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@18942 ce2b1a6d-e550-0410-aec6-3dcde31c8c00