Add sourcemap support to super dev mode. Source files work in Chrome canary
for everything except for super source. Also, enable super dev mode for
TourGuide's gin sample.

(This is a cleaned-up version of cromwellian's patch for the GWT summit.)

Review by: cromwellian@google.com

git-svn-id: https://google-web-toolkit.googlecode.com/svn/trunk@10836 8db76d5a-ed1c-0410-87a9-c151d255dfc7