LGTM. I ran some builds and checked the output - seemed fine and I didn't notice any impact on build times. I also scoured these types myself to look for other places to save and didn't find any others.
I'll keep StringInterner in the back of my mind. http://gwt-code-reviews.appspot.com/946801/show -- http://groups.google.com/group/Google-Web-Toolkit-Contributors
