add some more sky api to fakesky stub implementation.

sky/examples/fn/lib/fakesky.dart

Index: sky/examples/fn/lib/fakesky.dart
diff --git a/sky/examples/fn/lib/fakesky.dart b/sky/examples/fn/lib/fakesky.dart
index c2c72315d769bce43e70f0f0c77c094ff1fee57c..408616016aac3701702629f3bd49a269b1d59211 100644
--- a/sky/examples/fn/lib/fakesky.dart
+++ b/sky/examples/fn/lib/fakesky.dart
@@ -122,9 +122,11 @@ class HTMLImageElement extends Element {
   Object style = {};
 }
 
-class Event {
-  Event();
-}
+class Event {}
+
+class PointerEvent extends Event {}
+class GestureEvent extends Event {}
+class WheelEvent extends Event {}
 
 typedef EventListener(Event event);
 
@@ -146,3 +148,12 @@ class Window {
 Document document = new Document();
 
 Window window = new Window();
+
+class ClientRect {
+    double top
+    double right;
+    double bottomr;
+    double left;
+    double width;
+    double height;
+}