Check slot's distribution state more strictly

third_party/WebKit/Source/core/dom/shadow/SlotAssignment.cpp

 // Copyright 2015 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 "core/dom/shadow/SlotAssignment.h"
 
 #include "core/HTMLNames.h"
 #include "core/dom/ElementTraversal.h"
 #include "core/dom/NodeTraversal.h"
 #include "core/dom/shadow/ElementShadow.h"
@@ skipping 18 matching lines @@
 {
     m_assignment.clear();
 
     using Name2Slot = WillBeHeapHashMap<AtomicString, RefPtrWillBeMember<HTMLSlotElement>>;
     Name2Slot name2slot;
     HTMLSlotElement* defaultSlot = nullptr;
 
     const WillBeHeapVector<RefPtrWillBeMember<HTMLSlotElement>>& slots = shadowRoot.descendantSlots();
 
     for (RefPtrWillBeMember<HTMLSlotElement> slot : slots) {
-        slot->clearDistribution();
+        slot->willUpdateDistribution();
         AtomicString name = slot->fastGetAttribute(HTMLNames::nameAttr);
         if (name.isNull() || name.isEmpty()) {
             if (!defaultSlot)
                 defaultSlot = slot.get();
         } else {
             name2slot.add(name, slot.get());
         }
     }
 
     for (Node& child : NodeTraversal::childrenOf(*shadowRoot.host())) {
@@ skipping 44 matching lines @@
 }
 
 DEFINE_TRACE(SlotAssignment)
 {
 #if ENABLE(OILPAN)
     visitor->trace(m_assignment);
 #endif
 }
 
 } // namespace blink