CheckBox.ensureDebugId() now sets the ID of the input element.  Previously, it only set the ID of the label because the input element already had an ID.  I also updated RadioButtonTest because RadioButton is a subclass of CheckBox, but it did not have a test specifically for debug IDs.

Patch by: jlabanca
Review by: ajr
Issue: 2534



git-svn-id: https://google-web-toolkit.googlecode.com/svn/trunk@3071 8db76d5a-ed1c-0410-87a9-c151d255dfc7