Remove dead DataView IDL and C++ code

Source/core/dom/DOMDataView.h

Index: Source/core/dom/DOMDataView.h
diff --git a/Source/core/dom/DOMDataView.h b/Source/core/dom/DOMDataView.h
index c081de1d7b01afc54cfffcd3380e4ea2c27dd46a..51a40c3d2ca0b7ae94c57ed8118fb7297bba4b6d 100644
--- a/Source/core/dom/DOMDataView.h
+++ b/Source/core/dom/DOMDataView.h
@@ -6,7 +6,6 @@
 #define DOMDataView_h
 
 #include "core/dom/DOMArrayBufferView.h"
-#include "core/html/canvas/DataView.h"
 
 namespace blink {
 
@@ -17,14 +16,11 @@ public:
 
     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) { }
 };