Introduce FlexibleArrayBufferView and TypedFlexibleArrayBufferView

Source/core/dom/TypedFlexibleArrayBufferView.h

Index: Source/core/dom/TypedFlexibleArrayBufferView.h
diff --git a/Source/core/dom/TypedFlexibleArrayBufferView.h b/Source/core/dom/TypedFlexibleArrayBufferView.h
new file mode 100644
index 0000000000000000000000000000000000000000..814b4f2a54ed13abbe7481ec36c4981762af4f7d
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+++ b/Source/core/dom/TypedFlexibleArrayBufferView.h
@@ -0,0 +1,37 @@
+// Copyright 2015 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 TypedFlexibleArrayBufferView_h
+#define TypedFlexibleArrayBufferView_h
+
+#include "core/CoreExport.h"
+#include "core/dom/FlexibleArrayBufferView.h"
+#include "wtf/Noncopyable.h"
+
+namespace blink {
+
+template<typename WTFTypedArray>
+class CORE_TEMPLATE_CLASS_EXPORT TypedFlexibleArrayBufferView final : public FlexibleArrayBufferView {
+    STACK_ALLOCATED();
+    WTF_MAKE_NONCOPYABLE(TypedFlexibleArrayBufferView);
+public:
+    using ValueType = typename WTFTypedArray::ValueType;
+
+    TypedFlexibleArrayBufferView() : FlexibleArrayBufferView() {}
+
+    ValueType* dataMaybeOnStack() const { return static_cast<ValueType*>(baseAddressMaybeOnStack()); }
+
+    unsigned length() const
+    {
+        ASSERT(byteLength() % sizeof(ValueType) == 0);
+        return byteLength() / sizeof(ValueType);
+    }
+};
+
+using FlexibleInt32ArrayView = TypedFlexibleArrayBufferView<WTF::Int32Array>;
+using FlexibleFloat32ArrayView = TypedFlexibleArrayBufferView<WTF::Float32Array>;
+
+} // namespace blink
+
+#endif // TypedFlexibleArrayBufferView_h