Version 3.24.20

ES6: Implement Object.setPrototypeOf (issue 2675).

Performance and stability improvements on all platforms.

git-svn-id: https://v8.googlecode.com/svn/trunk@18702 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Merge remote-tracking branch 'upstream/trunk' into trunk