Refactor Future constructors.

sdk/lib/_internal/compiler/compiler.dart

 // 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.
 
 library compiler;
 
 import 'dart:async';
 import 'dart:uri';
 import 'implementation/apiimpl.dart';
 
@@ skipping 87 matching lines @@
   if (code != null && outputProvider != null) {
     String outputType = 'js';
     if (options.contains('--output-type=dart')) {
       outputType = 'dart';
     }
     outputProvider('', outputType)
         ..add(code)
         ..close();
     code = ''; // Non-null signals success.
   }
-  return new Future.immediate(code);
+  return new Future.value(code);
 }
 
 /**
  * Kind of diagnostics that the compiler can report.
  */
 class Diagnostic {
   /**
    * An error as identified by the "Dart Programming Language
    * Specification" [http://www.dartlang.org/docs/spec/].
    *
@@ skipping 49 matching lines @@
   final String name;
 
   /**
    * This constructor is not private to support user-defined
    * diagnostic kinds.
    */
   const Diagnostic(this.ordinal, this.name);
 
   String toString() => name;
 }