Move json2.js to a common location.

chrome/test/data/json2.js

 /*
     http://www.JSON.org/json2.js
     2008-11-19
 
     Public Domain.
 
     NO WARRANTY EXPRESSED OR IMPLIED. USE AT YOUR OWN RISK.
 
     See http://www.JSON.org/js.html
 
@@ skipping 458 matching lines @@
                 return typeof reviver === 'function' ?
                     walk({'': j}, '') : j;
             }
 
 // If the text is not JSON parseable, then a SyntaxError is thrown.
 
             throw new SyntaxError('JSON.parse');
         };
     }
 })();