Fix JsInliner, to properly handle name scope tracking after multi-level inlining.  Was causing local variable name collisions after obfuscation.
Fixes issue 5936.

Review at http://gwt-code-reviews.appspot.com/1472803


git-svn-id: https://google-web-toolkit.googlecode.com/svn/trunk@10432 8db76d5a-ed1c-0410-87a9-c151d255dfc7