Again restore r10697 now that LazyPanel support is more robust.

*** Original change description ***

Change default of UiBinder.useLazyWidgetBuilders to true, in
preparation for deleting the old code.

Review at http://gwt-code-reviews.appspot.com/1579803

Review by: rchandia@google.com

git-svn-id: https://google-web-toolkit.googlecode.com/svn/trunk@10720 8db76d5a-ed1c-0410-87a9-c151d255dfc7