anchor.diff:          js_ast.LiteralNull()
         else
           _visitExpression(node.message),
  -      js.escapedString(location.sourceUrl.toString()),
  +      _cacheUri(location.sourceUrl.toString()),
         // Lines and columns are typically printed with 1 based indexing.
         js.number(location.line + 1),
         js.number(location.column + 1),
  
positive.code:       moduleItems.insert(_constTableInsertionIndex, constTableBody);
        _constLazyAccessors.clear();
      }
  
      moduleItems.addAll(afterClassDefItems);
      afterClassDefItems.clear();
  
negative.code:     emitSignature('Setter', instanceSetters);
      emitSignature('StaticGetter', staticGetters);
      emitSignature('StaticSetter', staticSetters);
      body.add(runtimeStatement('setLibraryUri(#, #)',
          [className, _cacheUri(jsLibraryDebuggerName(c.enclosingLibrary))]));
  
      var instanceFields = <js_ast.Property>[];
      var staticFields = <js_ast.Property>[];
  