Extracts AbstractComposite<W> out of Composite, to allow type safe
calls to gwtWidget(). Deprecates ResizeComposite and replaces it with
RequiresResizeComposite, which moves the "must implement
RequireResize" requirement check to compile time.

Review at http://gwt-code-reviews.appspot.com/1453807

Review by: jlabanca@google.com

git-svn-id: https://google-web-toolkit.googlecode.com/svn/trunk@10290 8db76d5a-ed1c-0410-87a9-c151d255dfc7
11 files changed