Fixed issues when stressing compaction with WeakMaps.

Fixed missing GVN flag for new-space promotion. (Chromium issue 123919)

Simplify invocation sequence at monomorphic function invocation sites. (issue 2079)

Performance and stability improvements on all platforms.

git-svn-id: http://v8.googlecode.com/svn/trunk@11387 ce2b1a6d-e550-0410-aec6-3dcde31c8c00