Fixed crashes when calling new Array(a) with a single argument that could result in creating a holey array with a packed elements kind. (Chromium issue 245480)

Fixed issues in parallel compilation. (Chromium issue 248076)

Performance and stability improvements on all platforms.

git-svn-id: http://v8.googlecode.com/svn/trunk@15100 ce2b1a6d-e550-0410-aec6-3dcde31c8c00