Add TRACE_EVENT for common events in EventHandler

Source/core/events/EventDispatcher.cpp

Index: Source/core/events/EventDispatcher.cpp
diff --git a/Source/core/events/EventDispatcher.cpp b/Source/core/events/EventDispatcher.cpp
index 055273ab566bd337eee234d1b57c6bc12f1277c0..91a351e9dedb9900064a06617e27d6beeeafb17d 100644
--- a/Source/core/events/EventDispatcher.cpp
+++ b/Source/core/events/EventDispatcher.cpp
@@ -41,6 +41,7 @@ static HashSet<Node*>* gNodesDispatchingSimulatedClicks = 0;
 
 bool EventDispatcher::dispatchEvent(Node* node, PassRefPtr<EventDispatchMediator> mediator)
 {
+    TRACE_EVENT0("webkit", "EventDispatcher::dispatchEvent");
     ASSERT(!NoEventDispatchAssertion::isEventDispatchForbidden());
     if (!mediator->event())
         return true;
@@ -99,6 +100,8 @@ void EventDispatcher::dispatchSimulatedClick(Node* node, Event* underlyingEvent,
 
 bool EventDispatcher::dispatch()
 {
+    TRACE_EVENT0("webkit", "EventDispatcher::dispatch");
+
 #ifndef NDEBUG
     ASSERT(!m_eventDispatched);
     m_eventDispatched = true;