anchor.diff:        'name': libname,
         'size': size,
         'id': id,
  -      'children': children
  +      'children': children,
  +      'canonicalUri': element.canonicalUri.toString()
       };
     }
   
  
positive.code: 
      dart2jsVersion = compiler.hasBuildId ? compiler.buildId : null;
  
      for (var library in compiler.libraryLoader.libraries.toList()) {
        visit(library);
      }
    }
  
negative.code:   DumpInfoTask(Compiler compiler)
        : super(compiler);
  
    String get name => "Dump Info";
  
    ElementToJsonVisitor infoCollector;
  
  