Changing window.requestLayoutFrame into a microtask API

tools/dom/templates/html/dartium/impl_Window.darttemplate

 // Copyright (c) 2012, 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.
 
 part of html;
 
 $(ANNOTATIONS)class $CLASSNAME$EXTENDS$IMPLEMENTS$NATIVESPEC {
 
   /**
-   * Executes a [callback] after the next batch of browser layout measurements
-   * has completed or would have completed if any browser layout measurements
-   * had been scheduled.
+   * Executes a [callback] after the immediate execution stack has completed.
+   *
+   * This will cause the callback to be executed after all processing has
+   * completed for the current event, but before any subsequent events.
    */
-  void requestLayoutFrame(TimeoutHandler callback) {
-    _addMeasurementFrameCallback(callback);
+  void setImmediate(TimeoutHandler callback) {
+    _addMicrotaskCallback(callback);
   }
 
   /**
    * Lookup a port by its [name].  Return null if no port is
    * registered under [name].
    */
   lookupPort(String name) {
     var port = json.parse(document.documentElement.attributes['dart-port:$name']);
     return _deserialize(port);
   }
 
   /**
    * Register a [port] on this window under the given [name].  This
    * port may be retrieved by any isolate (or JavaScript script)
    * running in this window.
    */
   registerPort(String name, var port) {
     var serialized = _serialize(port);
     document.documentElement.attributes['dart-port:$name'] = json.stringify(serialized);
   }
 
+  /// Checks if _setImmediate is supported.
+  static bool get _supportsSetImmediate => false;
+
+  /// Dartium stub for IE's setImmediate.
+  void _setImmediate(void callback()) {
+    throw new UnsupportedError('setImmediate is not supported');
+  }
+
 $!MEMBERS
 }