Dispatch slotchange events in "notify mutation observers" steps

third_party/WebKit/Source/core/html/HTMLSlotElement.cpp

 /*
  * Copyright (C) 2015 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 131 matching lines @@
   m_distributedNodes.clear();
   m_distributedIndices.clear();
 }
 
 void HTMLSlotElement::saveAndClearDistribution() {
   m_oldDistributedNodes.swap(m_distributedNodes);
   clearDistribution();
 }
 
 void HTMLSlotElement::dispatchSlotChangeEvent() {
-  m_slotchangeEventEnqueued = false;
   Event* event = Event::createBubble(EventTypeNames::slotchange);
   event->setTarget(this);
   dispatchScopedEvent(event);
 }
 
 Node* HTMLSlotElement::distributedNodeNextTo(const Node& node) const {
   DCHECK(supportsDistribution());
   const auto& it = m_distributedIndices.find(&node);
   if (it == m_distributedIndices.end())
     return nullptr;
@@ skipping 162 matching lines @@
   DCHECK(root->isV1());
   root->owner()->setNeedsDistributionRecalc();
   // Check slotchange recursively since this slotchange may cause another
   // slotchange.
   checkSlotChange(SlotChangeType::Chained);
 }
 
 void HTMLSlotElement::enqueueSlotChangeEvent() {
   if (m_slotchangeEventEnqueued)
     return;
-  Microtask::enqueueMicrotask(WTF::bind(
-      &HTMLSlotElement::dispatchSlotChangeEvent, wrapPersistent(this)));
+  MutationObserver::enqueueSlotChange(*this);
   m_slotchangeEventEnqueued = true;
 }
 
 bool HTMLSlotElement::hasAssignedNodesSlow() const {
   ShadowRoot* root = containingShadowRoot();
   DCHECK(root);
   DCHECK(root->isV1());
   SlotAssignment& assignment = root->ensureSlotAssignment();
   if (assignment.findSlotByName(name()) != this)
     return false;
@@ skipping 14 matching lines @@
 
 DEFINE_TRACE(HTMLSlotElement) {
   visitor->trace(m_assignedNodes);
   visitor->trace(m_distributedNodes);
   visitor->trace(m_oldDistributedNodes);
   visitor->trace(m_distributedIndices);
   HTMLElement::trace(visitor);
 }
 
 }  // namespace blink