Version 3.27.8 (based on bleeding_edge revision r21370)

Move microtask queueing logic from JavaScript to C++.

Partial revert of "Next bunch of fixes for check elimination" (Chromium issue 372173).

Performance and stability improvements on all platforms.

git-svn-id: https://v8.googlecode.com/svn/trunk@21373 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Merge remote-tracking branch 'upstream/trunk' into trunk