Refactor Future constructors.

sdk/lib/_internal/dartdoc/lib/dartdoc.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.
 
 /**
  * To generate docs for a library, run this script with the path to an
  * entrypoint .dart file, like:
  *
  *     $ dart dartdoc.dart foo.dart
  *
@@ skipping 131 matching lines @@
     'outputDir': outputDir.toNativePath(),
     'libPath': libPath.toNativePath()
   }).then((result) {
     if (result.first == 'success') return;
     throw new AsyncError(result[1], result[2]);
   });
 }
 
 void _compileScript() {
   port.receive((message, replyTo) {
-    new Future.of(() {
+    new Future.sync(() {
       var clientScript = (message['mode'] == MODE_STATIC) ?
           'static' : 'live-nav';
       var dartPath = pathos.join(message['libPath'], 'lib', '_internal',
           'dartdoc', 'lib', 'src', 'client', 'client-$clientScript.dart');
       var jsPath = pathos.join(message['outputDir'], 'client-$clientScript.js');
 
       return dart2js.compile(
           new Path(dartPath), new Path(message['libPath']),
           options: const <String>['--categories=Client,Server']).then((jsCode) {
         writeString(new File(jsPath), jsCode);
@@ skipping 2152 matching lines @@
    return '''
         <div class="mdn">
         $mdnComment
         <div class="mdn-note"><a href="$mdnUrl">from MDN</a></div>
         </div>
         ''';
   }
 
   String toString() => mdnComment;
 }