Use Point<num> in dart:html for strong mode

tools/dom/templates/html/dart2js/impl_MouseEvent.darttemplate

 // 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.
 
 part of $LIBRARYNAME;
 
 $(ANNOTATIONS)$(NATIVESPEC)$(CLASS_MODIFIERS)class $CLASSNAME$EXTENDS$IMPLEMENTS {
   factory $CLASSNAME(String type,
       {Window view, int detail: 0, int screenX: 0, int screenY: 0,
       int clientX: 0, int clientY: 0, int button: 0, bool canBubble: true,
       bool cancelable: true, bool ctrlKey: false, bool altKey: false,
       bool shiftKey: false, bool metaKey: false, EventTarget relatedTarget}) {
 
     if (view == null) {
       view = window;
     }
     MouseEvent event = document._createEvent('MouseEvent');
     event._initMouseEvent(type, canBubble, cancelable, view, detail,
         screenX, screenY, clientX, clientY, ctrlKey, altKey, shiftKey, metaKey,
         button, relatedTarget);
     return event;
   }
 $!MEMBERS
 
   @DomName('MouseEvent.clientX')
   @DomName('MouseEvent.clientY')
-  Point get client => new Point(_clientX, _clientY);
+  Point get client => new Point/*<num>*/(_clientX, _clientY);
 
   @DomName('MouseEvent.movementX')
   @DomName('MouseEvent.movementY')
   @SupportedBrowser(SupportedBrowser.CHROME)
   @SupportedBrowser(SupportedBrowser.FIREFOX)
   @Experimental()
-  Point get movement => new Point(_movementX, _movementY);
+  Point get movement => new Point/*<num>*/(_movementX, _movementY);
 
   /**
    * The coordinates of the mouse pointer in target node coordinates.
    *
    * This value may vary between platforms if the target node moves
    * after the event has fired or if the element has CSS transforms affecting
    * it.
    */
   Point get offset {
     if (JS('bool', '!!#.offsetX', this)) {
       var x = JS('int', '#.offsetX', this);
       var y = JS('int', '#.offsetY', this);
-      return new Point(x, y);
+      return new Point/*<num>*/(x, y);
     } else {
       // Firefox does not support offsetX.
       if (!(this.target is Element)) {
         throw new UnsupportedError(
             'offsetX is only supported on elements');
       }
       Element target = this.target;
       var point = (this.client - target.getBoundingClientRect().topLeft);
-      return new Point(point.x.toInt(), point.y.toInt());
+      return new Point/*<num>*/(point.x.toInt(), point.y.toInt());
     }
   }
 
   @DomName('MouseEvent.screenX')
   @DomName('MouseEvent.screenY')
-  Point get screen => new Point(_screenX, _screenY);
+  Point get screen => new Point/*<num>*/(_screenX, _screenY);
 
   @DomName('MouseEvent.layerX')
   @DomName('MouseEvent.layerY')
-  Point get layer => new Point(_layerX, _layerY);
+  Point get layer => new Point/*<num>*/(_layerX, _layerY);
 
   @DomName('MouseEvent.pageX')
   @DomName('MouseEvent.pageY')
-  Point get page => new Point(_pageX, _pageY);
+  Point get page => new Point/*<num>*/(_pageX, _pageY);
 }