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

tools/dom/src/Point.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.
 
 part of html;
 
 /**
  * A utility class for representing two-dimensional positions.
  */
 class Point {
   final num x;
   final num y;
 
   const Point([num x = 0, num y = 0]): x = x, y = y;
 
   String toString() => '($x, $y)';
 
   bool operator ==(other) {
     if (other is !Point) return false;
     return x == other.x && y == other.y;
   }
 
+  int get hashCode => JenkinsSmiHash.hash2(x.hashCode, y.hashCode);
+
   Point operator +(Point other) {
     return new Point(x + other.x, y + other.y);
   }
 
   Point operator -(Point other) {
     return new Point(x - other.x, y - other.y);
   }
 
   Point operator *(num factor) {
     return new Point(x * factor, y * factor);
@@ skipping 22 matching lines @@
 
   Point ceil() => new Point(x.ceil(), y.ceil());
   Point floor() => new Point(x.floor(), y.floor());
   Point round() => new Point(x.round(), y.round());
 
   /**
    * Truncates x and y to integers and returns the result as a new point.
    */
   Point toInt() => new Point(x.toInt(), y.toInt());
 }