After a very hot local discussion :) we came to conclusion that we don't need CCLM to maintain ModuleDefs cache and can use HARD,SOFT map for top-level cache and ordinary map for moduleName->ModuleDef cache. I'll upload a new patch shortly.
http://gwt-code-reviews.appspot.com/1274801/show -- http://groups.google.com/group/Google-Web-Toolkit-Contributors
