Version 3.26.31 (based on bleeding_edge revision r21147)

Add a basic gn file for V8.

Performance and stability improvements on all platforms.

git-svn-id: https://v8.googlecode.com/svn/trunk@21152 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Merge remote-tracking branch 'upstream/trunk' into trunk