Changing window.requestLayoutFrame into a microtask API

tests/html/measurement_test.dart

-// Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
-// for details. All rights reserved. Use of this source code is governed by a
-// BSD-style license that can be found in the LICENSE file.
-
-library MeasurementTest;
-import '../../pkg/unittest/lib/unittest.dart';
-import '../../pkg/unittest/lib/html_config.dart';
-import 'dart:html';
-
-main() {
-  useHtmlConfiguration();
-
-  test('measurement is async but before setTimout 0', () {
-    final element = document.body;
-    bool fnComplete = false;
-    bool timeout0 = false;
-    window.setTimeout(() { timeout0 = true; }, 0);
-    final computedStyle = element.computedStyle;
-    computedStyle.then(expectAsync1((style) {
-      expect(style.getPropertyValue('left'), equals('auto'));
-      expect(fnComplete, isTrue);
-      expect(timeout0, isFalse);
-    }));
-    fnComplete = true;
-  });
-
-  test('requestLayoutFrame', () {
-    var computedStyle;
-    var computedStyleCalled = false;
-    window.requestLayoutFrame(expectAsync0(() {
-      expect(computedStyleCalled, true);
-    }));
-
-    final element = document.body;
-    computedStyle = element.computedStyle;
-    computedStyle.then(expectAsync1((style) {
-      computedStyleCalled = true;
-    }));
-  });
-
-  // TODO(jacobr): add more tests that the results return by measurement
-  // functions are correct.
-}