Remove remaining use of JSON.stringify() and replace with simple StringBuilder concatenation.
Patch by: bobv
Review by: cromwellian

Review at http://gwt-code-reviews.appspot.com/960801


git-svn-id: https://google-web-toolkit.googlecode.com/svn/trunk@8939 8db76d5a-ed1c-0410-87a9-c151d255dfc7