Add a "forwarded" flag to usergesture tokens.

Source/core/frame/DOMWindow.cpp

Index: Source/core/frame/DOMWindow.cpp
diff --git a/Source/core/frame/DOMWindow.cpp b/Source/core/frame/DOMWindow.cpp
index 1be25580cdf8821a5d4908e18cc287336b52db5f..606fbb5a1bba4e621a7f906c79f67d34fda9aa5c 100644
--- a/Source/core/frame/DOMWindow.cpp
+++ b/Source/core/frame/DOMWindow.cpp
@@ -864,7 +864,10 @@ void DOMWindow::postMessageTimerFired(PassOwnPtr<PostMessageTimer> t)
     if (m_frame->loader().client()->willCheckAndDispatchMessageEvent(timer->targetOrigin(), event.get()))
         return;
 
-    UserGestureIndicator gestureIndicator(timer->userGestureToken());
+    UserGestureToken* token = timer->userGestureToken();
+    if (token)
+        token->setForwarded();
+    UserGestureIndicator gestureIndicator(token);
 
     event->entangleMessagePorts(document());
     dispatchMessageEventWithOriginCheck(timer->targetOrigin(), event, timer->stackTrace());