Add the Presentation API module and a single event target

Source/modules/presentation/Presentation.idl

Index: Source/modules/presentation/Presentation.idl
diff --git a/Source/modules/gamepad/GamepadButton.idl b/Source/modules/presentation/Presentation.idl
similarity index 50%
copy from Source/modules/gamepad/GamepadButton.idl
copy to Source/modules/presentation/Presentation.idl
index 19d88ce77cdc808153c4250e1203526586640e01..1546a1dbd34d8fcd9b995e269d37a37cae91205f 100644
--- a/Source/modules/gamepad/GamepadButton.idl
+++ b/Source/modules/presentation/Presentation.idl
@@ -2,10 +2,11 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// http://webscreens.github.io/presentation-api/#presentation-interface
+
 [
-    NoInterfaceObject,
     GarbageCollected,
-] interface GamepadButton {
-    readonly attribute boolean pressed;
-    readonly attribute double value;
+    RuntimeEnabled=Presentation
+] interface Presentation : EventTarget {
+    attribute EventHandler onavailablechange;
 };