Add support for CefDragHandler::OnDragEnter (issue #601).

git-svn-id: http://chromiumembedded.googlecode.com/svn/trunk/cef3@1282 5089003a-bbd8-11dd-ad1f-f1f9622dbc98
Use chrome translations for most context menu strings (issue #992).

git-svn-id: http://chromiumembedded.googlecode.com/svn/trunk/cef3@1283 5089003a-bbd8-11dd-ad1f-f1f9622dbc98