Reland "Allow inlining of functions containing %_ArgumentsLength."

The layout test failures were unrelated to this change.

R=svenpanne@chromium.org
TBR=svenpanne@chromium.org

Review URL: https://codereview.chromium.org/355993002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@22038 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Infer whether a variable is assigned in inner functions

R=titzer@chromium.org
BUG=

Review URL: https://codereview.chromium.org/345573002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@22039 ce2b1a6d-e550-0410-aec6-3dcde31c8c00