Changing window.requestLayoutFrame into a microtask API

tests/html/cssstyledeclaration_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 CssStyleDeclarationTest;
 import '../../pkg/unittest/lib/unittest.dart';
 import '../../pkg/unittest/lib/html_config.dart';
 import 'dart:html';
 
 main() {
@@ skipping 54 matching lines @@
 
     expect(style.color, equals("red"));
     expect(style.transform, equals("translate(10px, 20px)"));
   });
 
   test('Browser prefixes', () {
     var element = new DivElement();
     element.style.transform = 'translateX(10px)';
     document.body.children.add(element);
 
-    element.getComputedStyle('').then(expectAsync1(
-      (CssStyleDeclaration style) {
-        // Some browsers will normalize this, so it'll be a matrix rather than
-        // the original string. Just check that it's something other than null.
-        expect(style.transform.length, greaterThan(3));
-      }
-    ));
+    var style = element.getComputedStyle();
+    // Some browsers will normalize this, so it'll be a matrix rather than
+    // the original string. Just check that it's something other than null.
+    expect(style.transform.length, greaterThan(3));
   });
 
   // IE9 requires an extra poke for some properties to get applied.
   test('IE9 Invalidation', () {
     var element = new DivElement();
     document.body.children.add(element);
 
     // Need to wait one tick after the element has been added to the page.
     window.setTimeout(expectAsync0(() {
       element.style.textDecoration = 'underline';
-      element.getComputedStyle('').then(expectAsync1(
-        (CssStyleDeclaration style) {
-          expect(style.textDecoration, equals('underline'));
-        }
-      ));
+      var style = element.getComputedStyle();
+      expect(style.textDecoration, equals('underline'));
     }), 10);
   });
 }