Support a @Timeout annotation.

lib/src/backend/metadata.dart

 // Copyright (c) 2015, 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 test.backend.metadata;
 
 import '../frontend/timeout.dart';
 import 'platform_selector.dart';
 
 /// Metadata for a test or test suite.
 ///
 /// This metadata comes from declarations on the test itself; it doesn't include
 /// configuration from the user.
 class Metadata {
   /// The selector indicating which platforms the suite supports.
   final PlatformSelector testOn;
 
   /// The modification to the timeout for the test or suite.
   final Timeout timeout;
 
   /// Creates new Metadata.
   ///
   /// [testOn] defaults to [PlatformSelector.all].
   Metadata({PlatformSelector testOn, Timeout timeout})
       : testOn = testOn == null ? PlatformSelector.all : testOn,
-        timeout = timeout == null ? new Timeout.factor(1) : timeout;
+        timeout = timeout == null ? const Timeout.factor(1) : timeout;
 
   /// Creates a new Metadata, but with fields parsed from strings where
   /// applicable.
   ///
   /// Throws a [FormatException] if any field is invalid.
   Metadata.parse({String testOn, Timeout timeout})
       : this(
           testOn: testOn == null ? null : new PlatformSelector.parse(testOn),
           timeout: timeout);
 
@@ skipping 19 matching lines @@
   serialize() => {
     'testOn': testOn == PlatformSelector.all ? null : testOn.toString(),
     'timeout': {
       'duration': timeout.duration == null
           ? null
           : timeout.duration.inMicroseconds,
       'scaleFactor': timeout.scaleFactor
     }
   };
 }