Adds design time hooks to UiBinder for GWT Designer, or any other tool
that can find a use for them. See discussion in
http://groups.google.com/group/google-web-toolkit-contributors/browse_thread/thread/3e9b2193531fb0b4/69829d19f0573be1

Patch by konstantin.scheglov@gmail.com
Review by rjrjr@google.com
http://gwt-code-reviews.appspot.com/693801/show

Review by: robertvawter@google.com

git-svn-id: https://google-web-toolkit.googlecode.com/svn/trunk@8384 8db76d5a-ed1c-0410-87a9-c151d255dfc7