Add a "forwarded" flag to usergesture tokens.

Source/core/frame/DOMTimer.cpp

Index: Source/core/frame/DOMTimer.cpp
diff --git a/Source/core/frame/DOMTimer.cpp b/Source/core/frame/DOMTimer.cpp
index 26a2133bf75c9e0179ce192dd206f50cf9dbc406..f6a587ccf0066c100166bbf8d319afa5ec0378ec 100644
--- a/Source/core/frame/DOMTimer.cpp
+++ b/Source/core/frame/DOMTimer.cpp
@@ -51,7 +51,8 @@ static inline bool shouldForwardUserGesture(int interval, int nestingLevel)
 {
     return UserGestureIndicator::processingUserGesture()
         && interval <= maxIntervalForUserGestureForwarding
-        && nestingLevel == 1; // Gestures should not be forwarded to nested timers.
+        && nestingLevel == 1
+        && !UserGestureIndicator::currentToken()->wasForwarded();
 }
 
 double DOMTimer::hiddenPageAlignmentInterval()
@@ -114,6 +115,8 @@ void DOMTimer::fired()
     timerNestingLevel = m_nestingLevel;
     ASSERT(!context->activeDOMObjectsAreSuspended());
     // Only the first execution of a multi-shot timer should get an affirmative user gesture indicator.
+    if (m_userGestureToken)
+        m_userGestureToken->setForwarded();
     UserGestureIndicator gestureIndicator(m_userGestureToken.release());
 
     InspectorInstrumentationCookie cookie = InspectorInstrumentation::willFireTimer(context, m_timeoutID);