Optimizes LongFromJSNIChecker's execution time significantly.  An initial sloppy pass of FindJSNIRefs quickly checks for problems; only if problems are found is a strict parse done.

Patch by: spoon
Review by: me


git-svn-id: https://google-web-toolkit.googlecode.com/svn/trunk@2611 8db76d5a-ed1c-0410-87a9-c151d255dfc7