This is necessary for monomorphic stubs that rely on instance types,
such as ArrayLength, StringLength and FunctionPrototype.

BUG=chromium:172345

Review URL: https://chromiumcodereview.appspot.com/12082023

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@13526 ce2b1a6d-e550-0410-aec6-3dcde31c8c00