Fixing analyzer warnings on overloading == but not get hashCode.

tests/html/point_test.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.
 
 library point_test;
 
 import 'dart:html';
 import '../../pkg/unittest/lib/unittest.dart';
 import '../../pkg/unittest/lib/html_config.dart';
 
@@ skipping 85 matching lines @@
     expect(b.round(), new Point(5, 10));
   });
 
   test('toInt', () {
     var a = new Point(5.1, 10.8);
     var b = a.toInt();
     expect(b, new Point(5, 10));
     expect(b.x is int, isTrue);
     expect(b.y is int, isTrue);
   });
+
+  test('hashCode', () {
+    var a = new Point(0, 1);
+    var b = new Point(0, 1);
+    expect(a.hashCode, b.hashCode);
+
+    var c = new Point(1, 0);
+    expect(a.hashCode == c.hashCode, isFalse);
+  });
 }