Use the single argument overload of WebFrame::create().

As of r252664, we no longer depend on storing the frame ID in Blink,
so we can simply use the one-argument version of WebFrame::create()
and delete the two argument overload once this lands.

BUG=314791
R=creis@chromium.org
TBR=bauerb@chromium.org, boliu@chromium.org, vitalybuka@chromium.org

Review URL: https://codereview.chromium.org/175543005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@252831 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 252831