Refactor Future constructors.

tests/compiler/dart2js/dart_backend_test.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.
 
 import "package:expect/expect.dart";
 import 'dart:async';
 import 'dart:uri';
 import 'parser_helper.dart';
 import 'mock_compiler.dart';
 import '../../../sdk/lib/_internal/compiler/compiler.dart';
@@ skipping 74 matching lines @@
 testDart2DartWithLibrary(
     String srcMain, String srcLibrary,
     {void continuation(String s), bool minify: false,
     bool stripTypes: false}) {
   fileUri(path) => new Uri.fromComponents(scheme: 'file', path: path);
 
   final scriptUri = fileUri('script.dart');
   final libUri = fileUri('mylib.dart');
 
   provider(uri) {
-    if (uri == scriptUri) return new Future.immediate(srcMain);
+    if (uri == scriptUri) return new Future.value(srcMain);
     if (uri.toString() == libUri.toString()) {
-      return new Future.immediate(srcLibrary);
+      return new Future.value(srcLibrary);
     }
     if (uri.path.endsWith('/core.dart')) {
-      return new Future.immediate(coreLib);
+      return new Future.value(coreLib);
     } else  if (uri.path.endsWith('/io.dart')) {
-      return new Future.immediate(ioLib);
+      return new Future.value(ioLib);
     } else if (uri.path.endsWith('/js_helper.dart')) {
-      return new Future.immediate(helperLib);
+      return new Future.value(helperLib);
     } else if (uri.path.endsWith('/html_dart2js.dart')) {
       // TODO(smok): The file should change to html_dartium at some point.
-      return new Future.immediate(htmlLib);
+      return new Future.value(htmlLib);
     } else if (uri.path.endsWith('/foreign_helper.dart')) {
-      return new Future.immediate(foreignLib);
+      return new Future.value(foreignLib);
     } else if (uri.path.endsWith('/isolate_helper.dart')) {
-      return new Future.immediate(isolateHelperLib);
+      return new Future.value(isolateHelperLib);
     }
-    return new Future.immediate('');
+    return new Future.value('');
   }
 
   handler(uri, begin, end, message, kind) {
     if (identical(kind, Diagnostic.ERROR) || identical(kind, Diagnostic.CRASH)) {
       Expect.fail('$uri: $begin-$end: $message [$kind]');
     }
   }
 
   final options = <String>['--output-type=dart'];
   // Some tests below are using dart:io.
@@ skipping 632 matching lines @@
   testStaticAccessIoLib();
   testLocalFunctionPlaceholder();
   testMinification();
   testClosureLocalsMinified();
   testParametersMinified();
   testDeclarationTypePlaceholders();
   testPlatformLibraryMemberNamesAreFixed();
   testConflictsWithCoreLib();
   testUnresolvedNamedConstructor();
 }