Get strong permutation from headers rather than serialized log record

Review at http://gwt-code-reviews.appspot.com/880802

Review by: fredsa@google.com

git-svn-id: https://google-web-toolkit.googlecode.com/svn/trunk@8834 8db76d5a-ed1c-0410-87a9-c151d255dfc7
14 files changed