Allow CrossThreadPersistent in collections

third_party/WebKit/Source/platform/heap/PersistentNode.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 "platform/heap/PersistentNode.h"
 
 #include "platform/heap/Handle.h"
 
 namespace blink {
 
@@ skipping 106 matching lines @@
             prevNext = &slots->m_next;
             slots = slots->m_next;
         }
     }
     ASSERT(persistentCount == m_persistentCount);
 }
 
 bool CrossThreadPersistentRegion::shouldTracePersistentNode(Visitor* visitor, PersistentNode* node)
 {
     CrossThreadPersistent<DummyGCBase>* persistent = reinterpret_cast<CrossThreadPersistent<DummyGCBase>*>(node->self());
-    ASSERT(persistent);
+    DCHECK(persistent);
+    DCHECK(!persistent->isHashTableDeletedValue());
     Address rawObject = reinterpret_cast<Address>(persistent->get());
     if (!rawObject)
         return false;
     return &visitor->heap() == &ThreadState::fromObject(rawObject)->heap();
 }
 
 void CrossThreadPersistentRegion::prepareForThreadStateTermination(ThreadState* threadState)
 {
     // For heaps belonging to a thread that's detaching, any cross-thread persistents
     // pointing into them needs to be disabled. Do that by clearing out the underlying
@@ skipping 24 matching lines @@
             if (page->arena()->getThreadState() == threadState) {
                 persistent->clear();
                 ASSERT(slots->m_slot[i].isUnused());
             }
         }
         slots = slots->m_next;
     }
 }
 
 } // namespace blink