Version 3.26.18 (based on bleeding_edge revision r20821)

Removed Isolate::EnterDefaultIsolate (Chromium issue 359977).

Performance and stability improvements on all platforms.

git-svn-id: https://v8.googlecode.com/svn/trunk@20826 ce2b1a6d-e550-0410-aec6-3dcde31c8c00