Moves PermutationResult from com.google.gwt.dev to com.google.gwt.dev.jjs.

This class is really an API from the compiler core, and moving it helps untangle some inter-package dependencies.

Review by: bobv

git-svn-id: https://google-web-toolkit.googlecode.com/svn/trunk@5821 8db76d5a-ed1c-0410-87a9-c151d255dfc7