Make InstanceRequest usable with value objects by changing the parameterization to BaseProxy. Add test for above. Fix bug in RequestFactoryInterfaceValidator where validateProxy() wouldn't actually validate. Issue 5678. Patch by: bobv Review by: rjrjr Review at http://gwt-code-reviews.appspot.com/1222801 git-svn-id: https://google-web-toolkit.googlecode.com/svn/trunk@9436 8db76d5a-ed1c-0410-87a9-c151d255dfc7