Remove dead DataView IDL and C++ code

Source/core/core.gypi

 {
     'includes': [
         'core_generated.gypi',
     ],
     'variables': {
         # Files for which bindings (.cpp and .h files) will be generated
         'core_idl_files': [
             'animation/KeyframeEffect.idl',
             'animation/EffectModel.idl',
             'animation/AnimationEffectReadOnly.idl',
@@ skipping 2785 matching lines @@
             'html/canvas/CanvasRenderingContext2D.cpp',
             'html/canvas/CanvasRenderingContext2D.h',
             'html/canvas/CanvasRenderingContext2DState.cpp',
             'html/canvas/CanvasRenderingContext2DState.h',
             'html/canvas/CanvasStyle.cpp',
             'html/canvas/CanvasStyle.h',
             'html/canvas/ContextAttributeHelpers.cpp',
             'html/canvas/ContextAttributeHelpers.h',
             'html/canvas/ClipList.cpp',
             'html/canvas/ClipList.h',
-            'html/canvas/DataView.cpp',
-            'html/canvas/DataView.h',
             'html/canvas/EXTBlendMinMax.cpp',
             'html/canvas/EXTBlendMinMax.h',
             'html/canvas/EXTFragDepth.cpp',
             'html/canvas/EXTFragDepth.h',
             'html/canvas/EXTShaderTextureLOD.cpp',
             'html/canvas/EXTShaderTextureLOD.h',
             'html/canvas/EXTTextureFilterAnisotropic.cpp',
             'html/canvas/EXTTextureFilterAnisotropic.h',
             'html/canvas/EXTsRGB.cpp',
             'html/canvas/EXTsRGB.h',
@@ skipping 1114 matching lines @@
             'style/ComputedStyleTest.cpp',
             'style/OutlineValueTest.cpp',
             'style/SVGComputedStyleTest.cpp',
             'testing/PrivateScriptTestTest.cpp',
             'timing/MemoryInfoTest.cpp',
             'workers/WorkerThreadTest.cpp',
             'xml/parser/SharedBufferReaderTest.cpp',
         ],
     }
 }