Check the next chain of a slotchange event correctly on a slotchange at a fallback slot

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 303 matching lines @@
 {
     if (!m_slotchangeEventEnqueued) {
         Microtask::enqueueMicrotask(WTF::bind(&HTMLSlotElement::dispatchSlotChangeEvent, wrapPersistent(this)));
         m_slotchangeEventEnqueued = true;
     }
 
     ShadowRoot* root = containingShadowRoot();
     DCHECK(root);
     DCHECK(root->isV1());
     root->owner()->setNeedsDistributionRecalc();
-
-    if (ShadowRoot* parentShadowRoot = v1ShadowRootOfParent()) {
-        if (HTMLSlotElement* next = parentShadowRoot->ensureSlotAssignment().findSlot(*this))
-            next->enqueueSlotChangeEvent();
-    }
+    // Check slotchange recursively since this slotchange may cause another slotchange.
+    checkSlotChange();
 }
 
 bool HTMLSlotElement::hasAssignedNodesSlow() const
 {
     ShadowRoot* root = containingShadowRoot();
     DCHECK(root);
     DCHECK(root->isV1());
     SlotAssignment& assignment = root->ensureSlotAssignment();
     if (assignment.findSlotByName(name()) != this)
         return false;
@@ skipping 17 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