Revert "Mojo: Add BindingsSupportImpl on top of HandleWatcher"

Review URL: https://codereview.chromium.org/69283002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@234252 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 234252