Code cleanup after "Fix handling of null passed into varargs."

http://gwt-code-reviews.appspot.com/1309801/show

Review by: cromwellian@google.com

git-svn-id: https://google-web-toolkit.googlecode.com/svn/trunk@9581 8db76d5a-ed1c-0410-87a9-c151d255dfc7