Introduce API to trigger exception on JS execution.

R=jochen@chromium.org, pmarch@chromium.org

Review URL: https://codereview.chromium.org/203223013

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@20070 ce2b1a6d-e550-0410-aec6-3dcde31c8c00