Re-land r8140: Deoptimize on never-executed code-paths.

Re-land r8140: Deoptimize on never-executed code-paths.

Original cl: http://codereview.chromium.org/7105015

I'm removing the test GlobalLoadICGC test that was introduced for testing
inlined global cell loads (in the classic backend) and has an invalid assumption
about the number of global objects referenced from a v8 context. We don't have
this feature with Crankshaft anymore.
Review URL: http://codereview.chromium.org/7112032

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@8185 ce2b1a6d-e550-0410-aec6-3dcde31c8c00