The failing mozilla test was caused by more deoptimizations
introduced by --always-opt and r11087.

We abort code generation in release mode, so we should do
the same in debug mode.
Review URL: https://chromiumcodereview.appspot.com/9752004

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@11091 ce2b1a6d-e550-0410-aec6-3dcde31c8c00