Previously we delayed the throwing of syntax errors until runtime, so
unreachable errors didn't get reported.
To match a change in JSC, we now stop parsing and report the error immediately.

BUG=69736
TEST=

Review URL: http://codereview.chromium.org/6355006

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@6341 ce2b1a6d-e550-0410-aec6-3dcde31c8c00