Remove some unused functions in core

Source/core/plugins/DOMMimeTypeArray.h

 /*
     Copyright (C) 2008 Nokia Corporation and/or its subsidiary(-ies)
     Copyright (C) 2008 Apple Inc. All rights reserved.
 
     This library is free software; you can redistribute it and/or
     modify it under the terms of the GNU Library General Public
     License as published by the Free Software Foundation; either
     version 2 of the License, or (at your option) any later version.
 
     This library is distributed in the hope that it will be useful,
@@ skipping 27 matching lines @@
     DEFINE_WRAPPERTYPEINFO();
     WILL_BE_USING_GARBAGE_COLLECTED_MIXIN(DOMMimeTypeArray);
 public:
     static PassRefPtrWillBeRawPtr<DOMMimeTypeArray> create(LocalFrame* frame)
     {
         return adoptRefWillBeNoop(new DOMMimeTypeArray(frame));
     }
 
     unsigned length() const;
     PassRefPtrWillBeRawPtr<DOMMimeType> item(unsigned index);
-    bool canGetItemsForName(const AtomicString& propertyName);
     PassRefPtrWillBeRawPtr<DOMMimeType> namedItem(const AtomicString& propertyName);
 
     virtual void trace(Visitor*) override;
 
 private:
     explicit DOMMimeTypeArray(LocalFrame*);
     PluginData* getPluginData() const;
 };
 
 } // namespace blink
 
 #endif // MimeTypeArray_h