Version 3.25.9 (based on bleeding_edge revision r19869)

Reland "Enable Object.observe by default" again (issue 2409).

Use intrinsics for builtin ArrayBuffer property accesses (Chromium issue 351787).

Performance and stability improvements on all platforms.

git-svn-id: https://v8.googlecode.com/svn/trunk@19870 ce2b1a6d-e550-0410-aec6-3dcde31c8c00