Add comment to PPB_MouseInputEvent version 1.1 that GetMovement hasn't been supported.

ppapi/native_client/src/shared/ppapi_proxy/browser_globals.cc

Index: ppapi/native_client/src/shared/ppapi_proxy/browser_globals.cc
diff --git a/ppapi/native_client/src/shared/ppapi_proxy/browser_globals.cc b/ppapi/native_client/src/shared/ppapi_proxy/browser_globals.cc
index 566dcf6fafefee68346e3528c08d6341ac7ff8a9..63e183fae7272f1fad8ed3feb850d0ab995daadc 100644
--- a/ppapi/native_client/src/shared/ppapi_proxy/browser_globals.cc
+++ b/ppapi/native_client/src/shared/ppapi_proxy/browser_globals.cc
@@ -278,6 +278,13 @@ const PPB_MouseInputEvent* PPBMouseInputEventInterface() {
   return ppb;
 }
 
+const PPB_MouseInputEvent_Dev* PPBMouseInputEventDevInterface() {
+  static const PPB_MouseInputEvent_Dev* ppb =
+      static_cast<const PPB_MouseInputEvent_Dev*>(
+          GetBrowserInterfaceSafe(PPB_MOUSE_INPUT_EVENT_DEV_INTERFACE));
+  return ppb;
+}
+
 const PPB_URLLoader* PPBURLLoaderInterface() {
   static const PPB_URLLoader* ppb =
       static_cast<const PPB_URLLoader*>(