Revert "GWT support for Chrome Frame"

This reverts commit r10250.

Fixes issue 6665.

Patch by: t.broyer
Review at https://gwt-code-reviews.appspot.com/1713803/

Review by: cromwellian@google.com

git-svn-id: https://google-web-toolkit.googlecode.com/svn/trunk@11045 8db76d5a-ed1c-0410-87a9-c151d255dfc7