If we have a property access of the form this.x, where the access site sees
the global object, we can specialize the IC stub so that it performs a map
check without first performing a heap object check.

Ensure that we do not get in JS code with a non-JSObject this value by
deoptimizing at Function.prototype.apply if the first argument is not a
JSObject.

BUG=v8:1128

Review URL: http://codereview.chromium.org/6463025

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@6707 ce2b1a6d-e550-0410-aec6-3dcde31c8c00