We can wrongly assume that exception which is not intended to be caught
by external try/catch should be caught if this exception inherits
external catcher from some previous exception.  To prevent that,
clear external catcher when processing exceptions which cannot be
externally caught.

BUG=v8:1184
TEST=test/mjsunit/regress/regress-1184.js

Review URL: http://codereview.chromium.org/6538081

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@6905 ce2b1a6d-e550-0410-aec6-3dcde31c8c00