Version 3.26.16 (based on bleeding_edge revision r20766)

Removed EnterIsolateIfNeeded and a soon-to-be-useless assertion (Chromium issue 359977).

Removed GetDefaultIsolate{Debugger,ForLocking,StackGuard} (Chromium issue 359977).

Performance and stability improvements on all platforms.

git-svn-id: https://v8.googlecode.com/svn/trunk@20779 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Merge remote-tracking branch 'upstream/trunk' into trunk