Revert of Implement /content/ combinator.

Source/core/css/CSSGrammar.y

Index: Source/core/css/CSSGrammar.y
diff --git a/Source/core/css/CSSGrammar.y b/Source/core/css/CSSGrammar.y
index 84e79237d064d4e3333a765d5d40a8f753527095..07267b223a96840023f426c59e2404a9241411f4 100644
--- a/Source/core/css/CSSGrammar.y
+++ b/Source/core/css/CSSGrammar.y
@@ -1055,8 +1055,6 @@ combinator:
             $$ = CSSSelector::Shadow;
         else if ($2.equalIgnoringCase("shadow-deep"))
             $$ = CSSSelector::ShadowDeep;
-        else if ($2.equalIgnoringCase("content"))
-            $$ = CSSSelector::ShadowContent;
         else
             YYERROR;
     }
@@ -1141,6 +1139,8 @@ selector:
         while (end->tagHistory())
             end = end->tagHistory();
         end->setRelation(CSSSelector::Descendant);
+        if ($1->isContentPseudoElement())
+            end->setRelationIsAffectedByPseudoContent();
         end->setTagHistory(parser->sinkFloatingSelector($1));
     }
     | selector combinator simple_selector {
@@ -1149,6 +1149,8 @@ selector:
         while (end->tagHistory())
             end = end->tagHistory();
         end->setRelation($2);
+        if ($1->isContentPseudoElement())
+            end->setRelationIsAffectedByPseudoContent();
         end->setTagHistory(parser->sinkFloatingSelector($1));
     }
     ;