More simplification of code now that RenderFrame is per WebFrame.

BUG=304341
R=nasko@chromium.org

Review URL: https://codereview.chromium.org/140243003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@246051 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 246051