for a SubStringStub and StringCompareStub in the ARM backend.  This
is a commit of http://codereview.chromium.org/3341012 for Andreas
Anyuru.
Review URL: http://codereview.chromium.org/3387003

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@5457 ce2b1a6d-e550-0410-aec6-3dcde31c8c00