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

third_party/WebKit/Source/core/css/SelectorChecker.cpp

Index: third_party/WebKit/Source/core/css/SelectorChecker.cpp
diff --git a/third_party/WebKit/Source/core/css/SelectorChecker.cpp b/third_party/WebKit/Source/core/css/SelectorChecker.cpp
index 3416c2386789fce0db221a12c9e35cd4d44c2431..581bee9feacab09d2ebf0f4b1bcb2d5423bdd978 100644
--- a/third_party/WebKit/Source/core/css/SelectorChecker.cpp
+++ b/third_party/WebKit/Source/core/css/SelectorChecker.cpp
@@ -917,6 +917,16 @@ bool SelectorChecker::checkPseudoClass(const SelectorCheckingContext& context, M
         return m_isUARule && matchesSpatialNavigationFocusPseudoClass(element);
     case CSSSelector::PseudoListBox:
         return m_isUARule && matchesListBoxPseudoClass(element);
+    case CSSSelector::PseudoHostHasAppearance:
+        if (!m_isUARule)
+            return false;
+        if (ShadowRoot* root = element.containingShadowRoot()) {
+            if (root->type() != ShadowRootType::UserAgent || !root->host())

[esprehn, 2016/05/13 22:18:40]

host() can't be null on a ShadowRoot

[tkent, 2016/05/16 00:21:25]

Removed the null check.

+                return false;
+            const ComputedStyle* style = root->host()->computedStyle();
+            return style && style->hasAppearance();
+        }
+        return false;
     case CSSSelector::PseudoWindowInactive:
         if (!context.hasSelectionPseudo)
             return false;
@@ -965,6 +975,12 @@ bool SelectorChecker::checkPseudoElement(const SelectorCheckingContext& context,
                 return root->type() == ShadowRootType::UserAgent && element.shadowPseudoId() == selector.value();
             return false;
         }
+    case CSSSelector::PseudoBlinkInternalElement:
+        if (!m_isUARule)
+            return false;
+        if (ShadowRoot* root = element.containingShadowRoot())
+            return root->type() == ShadowRootType::UserAgent && element.shadowPseudoId() == selector.value();
+        return false;
     case CSSSelector::PseudoSlotted:
         {
             SelectorCheckingContext subContext(context);