Add methods to allow resuming execution after calling TerminateExecution().

R=mvstanton@chromium.org
BUG=v8:2361

Review URL: https://chromiumcodereview.appspot.com/14401008

Patch from Andrew Paprocki <andrew@ishiboo.com>.

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@14378 ce2b1a6d-e550-0410-aec6-3dcde31c8c00