anchor.diff:  
     UnparseValidator(Compiler compiler, this.validateUnparse) : super(compiler);
   
  -  void check(Element element) {
  -    if (!validateUnparse) return;
  -
  -    // TODO(antonm): consider supporting other kinds of elements.
  -    if (element is! PartialFunctionElement) return;
  -
  -    PartialFunctionElement originalFunction = element;
  +  void checkFunction(PartialFunctionElement originalFunction) {
       FunctionExpression originalNode = originalFunction.parseNode(compiler);
       String unparsed = originalNode.unparse();
   
  
positive.code:         parser.findGetOrSet(parser.parseModifiers(newTokens));
  
      // TODO(ahe): This is also too frigging complicated.
      Script originalScript = element.getCompilationUnit().script;
      String name = SourceSpan.withOffsets(
          originalFunction.beginToken, originalFunction.endToken,
          (beginOffset, endOffset) =>
  
negative.code:     Script synthesizedScript =
          new Script(originalScript.uri, synthesizedSourceFile);
      LibraryElement lib = new LibraryElement(synthesizedScript);
      lib.canUseNative = originalFunction.getLibrary().canUseNative;
      NodeListener listener =
          new NodeListener(new ValidatorListener(synthesizedSourceFile), lib);
      parser = new Parser(listener);
  