Add some missing CSS prefixes. props `grunt autoprefixer:core`.

git-svn-id: https://develop.svn.wordpress.org/trunk@27790 602fd350-edb4-49c9-b593-d223f7449a82
Set the default font family to inherit (Open Sans) in all TinyMCE modals, change the cursor to pointer when hovering over Quicktags buttons. Props avryl, see #27279

git-svn-id: https://develop.svn.wordpress.org/trunk@27791 602fd350-edb4-49c9-b593-d223f7449a82