Use the provided key in all decisions about whether the selections have changed.

Review at http://gwt-code-reviews.appspot.com/1465802

Review by: jlabanca@google.com

git-svn-id: https://google-web-toolkit.googlecode.com/svn/trunk@10351 8db76d5a-ed1c-0410-87a9-c151d255dfc7