Bail out of any special-casing in array methods.
Further optimization is possible, but can be left for later.

Review URL: https://codereview.chromium.org/11369151
Patch from Adam Klein <adamk@chromium.org>.

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@12917 ce2b1a6d-e550-0410-aec6-3dcde31c8c00