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

third_party/WebKit/Source/core/css/CSSSelector.h

 /*
  * Copyright (C) 1999-2003 Lars Knoll (knoll@kde.org)
  *               1999 Waldo Bastian (bastian@kde.org)
  * Copyright (C) 2004, 2006, 2007, 2008, 2009, 2010, 2013 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
@@ skipping 175 matching lines @@
         PseudoSingleButton,
         PseudoNoButton,
         PseudoSelection,
         PseudoLeftPage,
         PseudoRightPage,
         PseudoFirstPage,
         PseudoFullScreen,
         PseudoFullScreenAncestor,
         PseudoInRange,
         PseudoOutOfRange,
+        // Pseudo elements in UA ShadowRoots. Available in any stylesheets.
         PseudoWebKitCustomElement,
+        // Pseudo elements in UA ShadowRoots. Availble only in UA stylesheets.
+        PseudoBlinkInternalElement,
         PseudoCue,
         PseudoFutureCue,
         PseudoPastCue,
         PseudoUnresolved,
         PseudoContent,
         PseudoHost,
         PseudoHostContext,
         PseudoShadow,
         PseudoSpatialNavigationFocus,
         PseudoListBox,
+        PseudoHostHasAppearance,
         PseudoSlotted
     };
 
     enum AttributeMatchType {
         CaseSensitive,
         CaseInsensitive,
     };
 
     PseudoType getPseudoType() const { return static_cast<PseudoType>(m_pseudoType); }
     void updatePseudoType(const AtomicString&, bool hasArguments);
@@ skipping 258 matching lines @@
     if (m_hasRareData)
         return m_data.m_rareData->m_serializingValue;
     // AtomicString is really just a StringImpl* so the cast below is safe.
     // FIXME: Perhaps call sites could be changed to accept StringImpl?
     return *reinterpret_cast<const AtomicString*>(&m_data.m_value);
 }
 
 } // namespace blink
 
 #endif // CSSSelector_h