Revert of Implement /content/ combinator.

Source/core/css/SelectorChecker.cpp

Index: Source/core/css/SelectorChecker.cpp
diff --git a/Source/core/css/SelectorChecker.cpp b/Source/core/css/SelectorChecker.cpp
index c419e53146dacc0e6810f6a3b43da62f076efa29..36d9f5f8c2ddee0301070505f5bd4d84b48fe9e4 100644
--- a/Source/core/css/SelectorChecker.cpp
+++ b/Source/core/css/SelectorChecker.cpp
@@ -151,6 +151,9 @@ SelectorChecker::Match SelectorChecker::match(const SelectorCheckingContext& con
         if (context.selector->isCustomPseudoElement()) {
             if (!matchesCustomPseudoElement(context.element, *context.selector))
                 return SelectorFailsLocally;
+        } else if (context.selector->isContentPseudoElement()) {
+            if (!context.element->isInShadowTree() || !context.element->isInsertionPoint())
+                return SelectorFailsLocally;
         } else {
             if ((!context.elementStyle && m_mode == ResolvingStyle) || m_mode == QueryingRules)
                 return SelectorFailsLocally;
@@ -273,10 +276,6 @@ SelectorChecker::Match SelectorChecker::matchForRelation(const SelectorCheckingC
             nextContext.elementStyle = 0;
             return match(nextContext, siblingTraversalStrategy, result);
         }
-
-    case CSSSelector::ShadowContent:
-        return matchForShadowDistributed(context.element, siblingTraversalStrategy, nextContext, result);
-
     case CSSSelector::DirectAdjacent:
         if (m_mode == ResolvingStyle) {
             if (ContainerNode* parent = context.element->parentElementOrShadowRoot())