when the code is run.

Instead, return an empty context handle so the failure to create a
context can be handled.

BUG=http://crbug.com/28486
Review URL: http://codereview.chromium.org/442005

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@3364 ce2b1a6d-e550-0410-aec6-3dcde31c8c00