Inline fast path for Array.indexOf() and Array.lastIndexOf().

TEST=mjsunit/array-indexing
R=mvstanton@chromium.org

Review URL: https://codereview.chromium.org/308793012

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@21617 ce2b1a6d-e550-0410-aec6-3dcde31c8c00