Rework dispatchEvent so it is consistent for isTrusted support.

Source/core/workers/WorkerEventQueue.cpp

Index: Source/core/workers/WorkerEventQueue.cpp
diff --git a/Source/core/workers/WorkerEventQueue.cpp b/Source/core/workers/WorkerEventQueue.cpp
index a8d52068d62ec21c33eb52c3a305fd15389c5e57..a3e677c3fc5ead4f5e57ab875d676590a61e8509 100644
--- a/Source/core/workers/WorkerEventQueue.cpp
+++ b/Source/core/workers/WorkerEventQueue.cpp
@@ -72,8 +72,13 @@ public:
             m_eventQueue->removeEvent(m_event.get());
     }
 
-    void dispatchEvent(ExecutionContext*, PassRefPtrWillBeRawPtr<Event> event)
+    void dispatchEvent(ExecutionContext*, PassRefPtrWillBeRawPtr<Event> prpEvent)
     {
+        // Stash the event on the stack in a RefPtrWillBeRawPtr; trying to do this
+        // in a single line causes an optimization bug with MSVC. MSVC generates code
+        // that passes the event arg (forcing PassRefPtrWillBeRawPtr to be released)
+        // before the target is queried.

[tkent, 2015/07/16 00:22:03]

Wow, nice detective work.

+        RefPtrWillBeRawPtr<Event> event = prpEvent;
         event->target()->dispatchEvent(event);
     }