Add support for GestureEvents to Sky

sky/engine/core/events/GestureEvent.idl

Index: sky/engine/core/events/GestureEvent.idl
diff --git a/sky/engine/core/events/GestureEvent.idl b/sky/engine/core/events/GestureEvent.idl
new file mode 100644
index 0000000000000000000000000000000000000000..7d44358eaf046eb5996f66dce77599a3d3c253a5
--- /dev/null
+++ b/sky/engine/core/events/GestureEvent.idl
@@ -0,0 +1,21 @@
+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+[
+    EventConstructor,
+] interface GestureEvent : UIEvent {
+    [InitializedByEventConstructor] readonly attribute long screenX;
+    [InitializedByEventConstructor] readonly attribute long screenY;
+    [InitializedByEventConstructor] readonly attribute long clientX;
+    [InitializedByEventConstructor] readonly attribute long clientY;
+    [InitializedByEventConstructor] readonly attribute boolean ctrlKey;
+    [InitializedByEventConstructor] readonly attribute boolean shiftKey;
+    [InitializedByEventConstructor] readonly attribute boolean altKey;
+    [InitializedByEventConstructor] readonly attribute boolean metaKey;
+
+    [InitializedByEventConstructor] readonly attribute double deltaX;
+    [InitializedByEventConstructor] readonly attribute double deltaY;
+    [InitializedByEventConstructor] readonly attribute double velocityX;
+    [InitializedByEventConstructor] readonly attribute double velocityY;
+};