Handle some failing DocumentOrderedMap ID lookups across tree removals.

third_party/WebKit/Source/core/dom/DocumentOrderedMap.h

 /*
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010 Apple 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 26 matching lines @@
 #include "wtf/HashMap.h"
 #include "wtf/text/AtomicString.h"
 #include "wtf/text/AtomicStringHash.h"
 #include "wtf/text/StringImpl.h"
 
 namespace blink {
 
 class Element;
 class TreeScope;
 
-class DocumentOrderedMap : public NoBaseWillBeGarbageCollectedFinalized<DocumentOrderedMap> {
+class DocumentOrderedMap : public NoBaseWillBeGarbageCollected<DocumentOrderedMap> {
     USING_FAST_MALLOC_WILL_BE_REMOVED(DocumentOrderedMap);
+    DECLARE_EMPTY_DESTRUCTOR_WILL_BE_REMOVED(DocumentOrderedMap);
 public:
     static PassOwnPtrWillBeRawPtr<DocumentOrderedMap> create();
-    ~DocumentOrderedMap();
 
     void add(const AtomicString&, Element*);
     void remove(const AtomicString&, Element*);
 
     bool contains(const AtomicString&) const;
     bool containsMultiple(const AtomicString&) const;
     // concrete instantiations of the get<>() method template
     Element* getElementById(const AtomicString&, const TreeScope*) const;
     const WillBeHeapVector<RawPtrWillBeMember<Element>>& getAllElementsById(const AtomicString&, const TreeScope*) const;
     Element* getElementByMapName(const AtomicString&, const TreeScope*) const;
     Element* getElementByLowercasedMapName(const AtomicString&, const TreeScope*) const;
     Element* getElementByLabelForAttribute(const AtomicString&, const TreeScope*) const;
 
     DECLARE_TRACE();
 
 #if ENABLE(ASSERT)
-    void willRemoveId(const AtomicString&);
+    // While removing a ContainerNode, ID lookups won't be precise should the tree
+    // have elements with duplicate IDs contained in the element being removed.
+    // Rare trees, but ID lookups may legitimately fail across such removals;
+    // this scope object informs DocumentOrderedMaps about the transitory
+    // state of the underlying tree.
+    class RemoveScope {
+        STACK_ALLOCATED();
+    public:
+        RemoveScope();
+        ~RemoveScope();
+    };
+#else
+    class RemoveScope {
+        STACK_ALLOCATED();
+    public:
+        RemoveScope() { }
+        ~RemoveScope() { }
+    };
 #endif
 
 private:
     DocumentOrderedMap();
 
     template<bool keyMatches(const AtomicString&, const Element&)>
     Element* get(const AtomicString&, const TreeScope*) const;
 
     class MapEntry : public NoBaseWillBeGarbageCollected<MapEntry> {
     public:
         explicit MapEntry(Element* firstElement)
             : element(firstElement)
             , count(1)
         {
         }
 
         DECLARE_TRACE();
 
         RawPtrWillBeMember<Element> element;
         unsigned count;
         WillBeHeapVector<RawPtrWillBeMember<Element>> orderedList;
     };
 
     using Map = WillBeHeapHashMap<AtomicString, OwnPtrWillBeMember<MapEntry>>;
 
     mutable Map m_map;
-#if ENABLE(ASSERT)
-    AtomicString m_removingId;
-#endif
 };
 
 inline bool DocumentOrderedMap::contains(const AtomicString& id) const
 {
     return m_map.contains(id);
 }
 
 inline bool DocumentOrderedMap::containsMultiple(const AtomicString& id) const
 {
     Map::const_iterator it = m_map.find(id);
     return it != m_map.end() && it->value->count > 1;
 }
 
 } // namespace blink
 
 #endif // DocumentOrderedMap_h