Intruducing AutoDirHandler, a handler for automatically adjusting the direction
of an object (typically a TextBox variant) while text is being entered. This
handler is then used to add BiDi support to TextBox and TextArea.

Review at http://gwt-code-reviews.appspot.com/386803

Review by: jat@google.com

git-svn-id: https://google-web-toolkit.googlecode.com/svn/trunk@8286 8db76d5a-ed1c-0410-87a9-c151d255dfc7