This patch adds a new method "UIObject.ensureDebugID(String)", which will add an ID to a Widget and its important sub elements.  Widgets which have important sub elements, such as the tabs in TabBar, override the onEnsureDebugId method to set the IDs.

Issue: 1898
Patch by: jlabanca
Review by: knorton


git-svn-id: https://google-web-toolkit.googlecode.com/svn/trunk@1783 8db76d5a-ed1c-0410-87a9-c151d255dfc7