Make dispatchIfAlive ensure the life of its queue.

Source/core/dom/custom/CustomElementMicrotaskRunQueue.cpp

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "config.h"
 #include "core/dom/custom/CustomElementMicrotaskRunQueue.h"
 
 #include "core/dom/Microtask.h"
 #include "core/dom/custom/CustomElementAsyncImportMicrotaskQueue.h"
 #include "core/dom/custom/CustomElementSyncMicrotaskQueue.h"
@@ skipping 22 matching lines @@
             m_syncQueue->enqueue(step);
     } else {
         m_asyncQueue->enqueue(step);
     }
 
     requestDispatchIfNeeded();
 }
 
 void CustomElementMicrotaskRunQueue::dispatchIfAlive(WeakPtr<CustomElementMicrotaskRunQueue> self)
 {
-    if (self.get())
+    if (self.get()) {
+        RefPtrWillBeRawPtr<CustomElementMicrotaskRunQueue> protect(self.get());
         self->dispatch();
+    }
 }
 
 void CustomElementMicrotaskRunQueue::requestDispatchIfNeeded()
 {
     if (m_dispatchIsPending || isEmpty())
         return;
     Microtask::enqueueMicrotask(WTF::bind(&CustomElementMicrotaskRunQueue::dispatchIfAlive, m_weakFactory.createWeakPtr()));
     m_dispatchIsPending = true;
 }
 
@@ skipping 10 matching lines @@
     if (m_syncQueue->isEmpty())
         m_asyncQueue->dispatch();
 }
 
 bool CustomElementMicrotaskRunQueue::isEmpty() const
 {
     return m_syncQueue->isEmpty() && m_asyncQueue->isEmpty();
 }
 
 } // namespace blink