Pipe detailed information (including stack trace) about runtime JS errors caused by extensions from the WebKit side over to the Chrome side.

Goes with: https://codereview.chromium.org/18799006/

See Also: https://docs.google.com/a/google.com/document/d/1moGXfxo6BbulkoCWISlKq2aQR_buVYGeGhDj6_bqMXk/edit

BUG=21734

Review URL: https://chromiumcodereview.appspot.com/18822004

git-svn-id: svn://svn.chromium.org/blink/trunk@156645 bbb929c8-8fbe-4397-9dbb-9b2b20218538