Version 3.28.4 (based on bleeding_edge revision r22031)

Compile optimized code with active debugger but no break points (Chromium issue 386492).

Optimize Map/Set.prototype.forEach.

Collect garbage with kReduceMemoryFootprintMask in IdleNotification (Chromium issue 350720).

Performance and stability improvements on all platforms.

git-svn-id: https://v8.googlecode.com/svn/trunk@22032 ce2b1a6d-e550-0410-aec6-3dcde31c8c00