This patch fixes a corner case in the XSSAuditor where the attacker can use an organically-occurring script tag to bypass the auditor. The trick is that injection<script>expr may be parsed by JS as (injection < script) > expr.

BUG=354109

Review URL: https://codereview.chromium.org/205243002

git-svn-id: svn://svn.chromium.org/blink/trunk@169697 bbb929c8-8fbe-4397-9dbb-9b2b20218538