dart2js: get:hashCode methods to avoid Object.hashCode

pkg/compiler/lib/src/common/tasks.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 dart2js.common.tasks;
 
 import 'dart:async'
     show Future, Zone, ZoneDelegate, ZoneSpecification, runZoned;
 
 /// Used to measure where time is spent in the compiler.
@@ skipping 193 matching lines @@
   /// Note: MUST be the first field of this class to ensure [wallclock] is
   /// started before other computations.
   final Stopwatch wallClock = new Stopwatch()..start();
 
   /// Measures gaps between zoned closures due to asynchronicity.
   final Stopwatch asyncWallClock = new Stopwatch();
 
   /// Whether measurement of tasks is enabled.
   final bool enableTaskMeasurements;
 
+  static int _hashCodeGenerator = 197;
+  final int hashCode = _hashCodeGenerator++;
+
   Measurer({this.enableTaskMeasurements: false});
 
   /// The currently running task, that is, the task whose [Stopwatch] is
   /// currently running.
   CompilerTask currentTask;
 
   /// The current task which should be charged for asynchronous gaps.
   CompilerTask currentAsyncTask;
 
   /// Start counting the total elapsed time since the compiler started.
@@ skipping 16 matching lines @@
   }
 
   /// Call this when the eventloop returns control to us.
   void stopAsyncWallClock() {
     if (currentAsyncTask != null) {
       currentAsyncTask._watch.stop();
     }
     asyncWallClock.stop();
   }
 }