Reland "Allow ICs to be generated for own global proxy."

BUG=
R=dcarney@chromium.org

Review URL: https://codereview.chromium.org/170343002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@19430 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Remove unnecessary checks in CompileStoreInterceptor on a64.

BUG=
R=dcarney@chromium.org

Review URL: https://codereview.chromium.org/163963003

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@19431 ce2b1a6d-e550-0410-aec6-3dcde31c8c00