Have Chrome Frame "support" IE conditional comment tags (of the...

Have Chrome Frame "support" IE conditional comment tags (of the downlevel-hidden variety) by ignoring them (rather than treating them as comment start/end) when parsing HTML streams.

BUG=65627
TEST=chrome_frame_unittests.exe, also syntax like <!--[if IE]><meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1"><![endif]-->  will now activate CF. 

Offtopic: I wonder what happens if I paste HTML into CL comments. Heh.


Review URL: http://codereview.chromium.org/5708007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@69177 0039d316-1c4b-4281-b951-d872f2087c98