add some more sky api to fakesky stub implementation.

sky/examples/fn/lib/fakesky.dart

 import 'dart:async';
 
 void assertHasParentNode(Node n) { assert(n.parentNode != null); }
 void assertHasParentNodes(List<Node> list) {
   for (var n in list) {
     assertHasParentNode(n);
   }
 }
 
 class Node {
@@ skipping 104 matching lines @@
     }
   }
 }
 
 class HTMLImageElement extends Element {
   Image();
   String src;
   Object style = {};
 }
 
-class Event {
-  Event();
-}
+class Event {}
+
+class PointerEvent extends Event {}
+class GestureEvent extends Event {}
+class WheelEvent extends Event {}
 
 typedef EventListener(Event event);
 
 void _callRAF(Function fn) {
   fn(new DateTime.now().millisecondsSinceEpoch.toDouble());
 }
 
 class Window {
   int requestAnimationFrame(Function fn) {
     new Timer(const Duration(milliseconds: 16), () {
       _callRAF(fn);
     });
   }
 
   void cancelAnimationFrame(int id) {
   }
 }
 
 Document document = new Document();
 
 Window window = new Window();
+
+class ClientRect {
+    double top
+    double right;
+    double bottomr;
+    double left;
+    double width;
+    double height;
+}