Rename runAsync to scheduleMicrotask.

tests/lib/async/intercept_run_async2_test.dart

 // Copyright (c) 2013, 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.
 
 import "package:expect/expect.dart";
 import 'dart:async';
 
 var events = [];
 
 body() {
   events.add("body entry");
-  runAsync(() {
+  scheduleMicrotask(() {
     events.add("run async body");
   });
   return 499;
 }
 
 handler(fun) {
   events.add("handler");
   fun();
   events.add("handler done");
 }
 
 main() {
-  // Test that runAsync interception works.
-  var result = runZonedExperimental(body, onRunAsync: handler);
+  // Test that scheduleMicrotask interception works.
+  var result = runZonedExperimental(body, onScheduleMicrotask: handler);
   // No need for a ReceivePort: If the runZonedExperimental disbehaved we
   // would have an [events] list that is different from what we expect.
   Expect.listEquals(["body entry", "handler", "run async body", "handler done"],
                     events);
 }