Remove warnings about x-webkit-deflate-frame

The expected output for layout test reserved-bits.html contains warnings
about the deprecation of x-webkit-deflate-frame. Since the new
implementation doens't have that extension or those warnings, remove them.

BUG=346211

Review URL: https://codereview.chromium.org/181303002

git-svn-id: svn://svn.chromium.org/blink/trunk@168289 bbb929c8-8fbe-4397-9dbb-9b2b20218538