Change global to window in SyntheticClipboardEvent

Replace `global` reference with `window` in `SyntheticClipboardEvent`.

src/event/synthetic/SyntheticClipboardEvent.js

@@ -30,7 +30,7 @@ var ClipboardEventInterface = {
     return (
       'clipboardData' in event ?
         event.clipboardData :
-        global.clipboardData
+        window.clipboardData
     );
   }
 };