Introduce :-internal-shadow-host-has-appearance pseudo class, and apply it to METER element.

third_party/WebKit/Source/core/html/shadow/AppearanceSwitchElement.h

-// Copyright 2016 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 AppearanceSwitchElement_h
-#define AppearanceSwitchElement_h
-
-#include "core/html/HTMLDivElement.h"
-
-namespace blink {
-
-class AppearanceSwitchElement final : public HTMLDivElement {
-public:
-    enum Mode {
-        ShowIfHostHasAppearance,
-        ShowIfHostHasNoAppearance,
-    };
-    static AppearanceSwitchElement* create(Document&, Mode);
-
-private:
-    AppearanceSwitchElement(Document&, Mode);
-    PassRefPtr<ComputedStyle> customStyleForLayoutObject() override;
-
-    const Mode m_mode;
-};
-
-} // namespace blink
-#endif // AppearanceSwitchElement_h