Allows CSS @def declarations to be retrieved as a String in a CssResource
implementation.  Detection was added for colliding class names and @def names,
but you can dis-ambiguate them with the @ClassName() annotation.

Patch by: zundel
Review by: bobv


git-svn-id: https://google-web-toolkit.googlecode.com/svn/trunk@5664 8db76d5a-ed1c-0410-87a9-c151d255dfc7