bindings: Add C++ versions of WebIDL types and generalize NativeValueTraits.

third_party/WebKit/Source/bindings/core/v8/NativeValueTraitsTest.cpp

+// Copyright (c) 2017 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.
+
+#include "bindings/core/v8/NativeValueTraits.h"
+
+#include <type_traits>
+#include "bindings/core/v8/IDLTypesBase.h"
+
+// No gtest tests; only static_assert checks.
+
+namespace blink {
+
+template <>
+struct NativeValueTraits<bool> : public NativeValueTraitsBase<bool> {};
+
+static_assert(std::is_same<NativeValueTraits<bool>::ImplType, bool>::value,
+              "NativeValueTraitsBase works with non IDLBase-derived types");
+
+struct MyIDLType final : public IDLBaseHelper<char> {};
+template <>
+struct NativeValueTraits<MyIDLType> : public NativeValueTraitsBase<MyIDLType> {
+};
+
+static_assert(std::is_same<NativeValueTraits<MyIDLType>::ImplType, char>::value,
+              "NativeValueTraitsBase works with IDLBase-derived types");
+
+}  // namespace blink