Test case for when the XSS vector is in the path.

We don't cover this very well at the moment, assuming instead that
the path portion of the URL is handled in the same way as the query
args (and in fact, the code doesn't break down the URL to distinguish
these in any way so this seemed reasonable).

BUG=330972

Review URL: https://codereview.chromium.org/125513003

git-svn-id: svn://svn.chromium.org/blink/trunk@164746 bbb929c8-8fbe-4397-9dbb-9b2b20218538