anchor.diff:        expect(checkbox2.checked, isFalse);
   
         // Change the values.
  -      customElement.value = 'not zag';
  +      customElement.set("value", 'not zag');
         input.value = 'not bar';
         checkbox1.checked = false;
         checkbox2.checked = true;
  
positive.code: 
        form.on['iron-form-response'].take(1).listen((event) {
          expect(submitted, isTrue);
          expect(convertToDart(event).detail.url, contains('zig=zag'));
  
          var response = convertToDart(event).detail.response;
          expect(response, isNotNull);
  
negative.code:         expect(presubmitted, isTrue);
  
          // We have changed the json parameters
          var url = convertToDart(event).detail.xhr['responseURL'];
          expect(url, contains('batman=true'));
  
          var response = convertToDart(event).detail.response;
          expect(response, isNotNull);
  