There was a comment that, for such ICs specialized to the global object,
they were always contextual loads.  This is very brittle.  It is a
micro-optimization that relies too much on the way that things happen to
work today.

Instead, never omit the smi check because it's safer.

R=vegorov@chromium.org
BUG=117794
TEST=regress-117794.js

Review URL: https://chromiumcodereview.appspot.com/9691038

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@11022 ce2b1a6d-e550-0410-aec6-3dcde31c8c00