DOM: Fix an incorrect result of getElementsByClassName() in quirks mode.

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

 /*
  * Copyright (C) 2007 Apple Inc. All rights reserved.
  * Copyright (C) 2007 David Smith (catfish.man@gmail.com)
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
@@ skipping 39 matching lines @@
   }
 
   ~ClassCollection() override;
 
   bool ElementMatches(const Element&) const;
 
  private:
   ClassCollection(ContainerNode& root_node, const AtomicString& class_names);
 
   SpaceSplitString class_names_;
-  AtomicString original_class_names_;
 };
 
 DEFINE_TYPE_CASTS(ClassCollection,
                   LiveNodeListBase,
                   collection,
                   collection->GetType() == kClassCollectionType,
                   collection.GetType() == kClassCollectionType);
 
 inline bool ClassCollection::ElementMatches(const Element& test_element) const {
   if (!test_element.HasClass())
     return false;
   if (!class_names_.size())
     return false;
   return test_element.ClassNames().ContainsAll(class_names_);
 }
 
 }  // namespace blink
 
 #endif  // ClassCollection_h