When making a static implementation method, set the original parameter types
of the new method based on the *original* parameter types of the old method,
not the *current* ones.

Review by: scottb (desk check)

git-svn-id: https://google-web-toolkit.googlecode.com/svn/trunk@2974 8db76d5a-ed1c-0410-87a9-c151d255dfc7