Remove dead DataView IDL and C++ code

Source/core/dom/DOMDataView.h

 // Copyright 2014 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.
 
 #ifndef DOMDataView_h
 #define DOMDataView_h
 
 #include "core/dom/DOMArrayBufferView.h"
-#include "core/html/canvas/DataView.h"
 
 namespace blink {
 
 class DOMDataView final : public DOMArrayBufferView {
     DEFINE_WRAPPERTYPEINFO();
 public:
     typedef char ValueType;
 
     static PassRefPtr<DOMDataView> create(PassRefPtr<DOMArrayBuffer>, unsigned byteOffset, unsigned byteLength);
 
-    const DataView* view() const { return static_cast<const DataView*>(DOMArrayBufferView::view()); }
-    DataView* view() { return static_cast<DataView*>(DOMArrayBufferView::view()); }
-
     virtual v8::Local<v8::Object> wrap(v8::Isolate*, v8::Local<v8::Object> creationContext) override;
     virtual v8::Local<v8::Object> associateWithWrapper(v8::Isolate*, const WrapperTypeInfo*, v8::Local<v8::Object> wrapper) override;
 
 private:
-    DOMDataView(PassRefPtr<DataView> dataView, PassRefPtr<DOMArrayBuffer> domArrayBuffer)
+    DOMDataView(PassRefPtr<WTF::ArrayBufferView> dataView, PassRefPtr<DOMArrayBuffer> domArrayBuffer)
         : DOMArrayBufferView(dataView, domArrayBuffer) { }
 };
 
 } // namespace blink
 
 #endif // DOMDataView_h