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

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

-// 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.
-
-#include "core/html/shadow/AppearanceSwitchElement.h"
-
-#include "core/dom/NodeComputedStyle.h"
-
-namespace blink {
-
-inline AppearanceSwitchElement::AppearanceSwitchElement(Document& doc, Mode mode)
-    : HTMLDivElement(doc)
-    , m_mode(mode)
-{
-    setHasCustomStyleCallbacks();
-}
-
-AppearanceSwitchElement* AppearanceSwitchElement::create(Document& doc, Mode mode)
-{
-    return new AppearanceSwitchElement(doc, mode);
-}
-
-PassRefPtr<ComputedStyle> AppearanceSwitchElement::customStyleForLayoutObject()
-{
-    // We can't use setInlineStyleProperty() because it updates the DOM tree.
-    // We shouldn't do it during style calculation.
-    // TODO(tkent): Injecting a CSS variable by host is a better approach?
-    Element* host = shadowHost();
-    RefPtr<ComputedStyle> style = originalStyleForLayoutObject();
-    if (!host || !host->computedStyle())
-        return style.release();
-    if (m_mode == ShowIfHostHasAppearance) {
-        if (host->computedStyle()->hasAppearance())
-            return style.release();
-    } else {
-        if (!host->computedStyle()->hasAppearance())
-            return style.release();
-    }
-    if (style->display() == NONE)
-        return style.release();
-    RefPtr<ComputedStyle> newStyle = ComputedStyle::clone(*style);
-    newStyle->setDisplay(NONE);
-    newStyle->setUnique();
-    return newStyle.release();
-}
-
-} // namespace blink