Remove unused V8 integration code in Sky

sky/engine/bindings/core/v8/V8HiddenValue.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 SKY_ENGINE_BINDINGS_CORE_V8_V8HIDDENVALUE_H_
-#define SKY_ENGINE_BINDINGS_CORE_V8_V8HIDDENVALUE_H_
-
-#include "sky/engine/bindings/core/v8/ScopedPersistent.h"
-#include "sky/engine/bindings/core/v8/ScriptPromiseProperties.h"
-#include "v8/include/v8.h"
-
-namespace blink {
-
-class ScriptWrappable;
-
-#define V8_HIDDEN_VALUES(V) \
-    V(arrayBufferData) \
-    V(customElementAttachedCallback) \
-    V(customElementAttributeChangedCallback) \
-    V(customElementCreatedCallback) \
-    V(customElementDetachedCallback) \
-    V(customElementDocument) \
-    V(customElementIsInterfacePrototypeObject) \
-    V(customElementNamespaceURI) \
-    V(customElementTagName) \
-    V(callback) \
-    V(condition) \
-    V(data) \
-    V(detail) \
-    V(document) \
-    V(error) \
-    V(idbCursorRequest) \
-    V(port1) \
-    V(port2) \
-    V(state) \
-    V(stringData) \
-    V(scriptState) \
-    V(thenableHiddenPromise) \
-    V(toStringString) \
-    SCRIPT_PROMISE_PROPERTIES(V, Promise)  \
-    SCRIPT_PROMISE_PROPERTIES(V, Resolver)
-
-class V8HiddenValue {
-public:
-#define V8_DECLARE_METHOD(name) static v8::Handle<v8::String> name(v8::Isolate* isolate);
-    V8_HIDDEN_VALUES(V8_DECLARE_METHOD);
-#undef V8_DECLARE_METHOD
-
-    static v8::Local<v8::Value> getHiddenValue(v8::Isolate*, v8::Handle<v8::Object>, v8::Handle<v8::String>);
-    static bool setHiddenValue(v8::Isolate*, v8::Handle<v8::Object>, v8::Handle<v8::String>, v8::Handle<v8::Value>);
-    static bool deleteHiddenValue(v8::Isolate*, v8::Handle<v8::Object>, v8::Handle<v8::String>);
-    static v8::Local<v8::Value> getHiddenValueFromMainWorldWrapper(v8::Isolate*, ScriptWrappable*, v8::Handle<v8::String>);
-
-private:
-#define V8_DECLARE_FIELD(name) ScopedPersistent<v8::String> m_##name;
-    V8_HIDDEN_VALUES(V8_DECLARE_FIELD);
-#undef V8_DECLARE_FIELD
-};
-
-} // namespace blink
-
-#endif  // SKY_ENGINE_BINDINGS_CORE_V8_V8HIDDENVALUE_H_