Previously we omitted all cases where the global eval property was shadowed,
even if by a variable holding the same value. ES5 requires us to treat these
as direct calls.

We still throw if calling indirect eval with a detached global object.

BUG=v8:994
TEST=mjsunit/eval.js

Review URL: http://codereview.chromium.org/8343054

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@9838 ce2b1a6d-e550-0410-aec6-3dcde31c8c00