*** NOT FOR LANDING *** Unprefix multicol behind a flag

Source/core/css/parser/CSSParserFastPaths.cpp

Index: Source/core/css/parser/CSSParserFastPaths.cpp
diff --git a/Source/core/css/parser/CSSParserFastPaths.cpp b/Source/core/css/parser/CSSParserFastPaths.cpp
index 846fd07242611f240e33c64cd22ae262844bf3a8..efcc743143c7be7c67348e6a6cecfb4d01494246 100644
--- a/Source/core/css/parser/CSSParserFastPaths.cpp
+++ b/Source/core/css/parser/CSSParserFastPaths.cpp
@@ -131,7 +131,6 @@ static inline bool isColorPropertyID(CSSPropertyID propertyId)
     case CSSPropertyWebkitBorderBeforeColor:
     case CSSPropertyWebkitBorderEndColor:
     case CSSPropertyWebkitBorderStartColor:
-    case CSSPropertyWebkitColumnRuleColor:
     case CSSPropertyWebkitTextEmphasisColor:
     case CSSPropertyWebkitTextFillColor:
     case CSSPropertyWebkitTextStrokeColor:
@@ -191,7 +190,6 @@ bool CSSParserFastPaths::isValidKeywordPropertyAndValue(CSSPropertyID propertyId
     case CSSPropertyWebkitBorderBeforeStyle:
     case CSSPropertyWebkitBorderEndStyle:
     case CSSPropertyWebkitBorderStartStyle:
-    case CSSPropertyWebkitColumnRuleStyle:
         return valueID >= CSSValueNone && valueID <= CSSValueDouble;
     case CSSPropertyBoxSizing:
         return valueID == CSSValueBorderBox || valueID == CSSValueContentBox;
@@ -308,7 +306,7 @@ bool CSSParserFastPaths::isValidKeywordPropertyAndValue(CSSPropertyID propertyId
     case CSSPropertyWebkitBoxPack:
         return valueID == CSSValueStart || valueID == CSSValueEnd || valueID == CSSValueCenter || valueID == CSSValueJustify;
     case CSSPropertyColumnFill:
-        ASSERT(RuntimeEnabledFeatures::regionBasedColumnsEnabled());
+        ASSERT(RuntimeEnabledFeatures::unprefixMulticolEnabled());
         return valueID == CSSValueAuto || valueID == CSSValueBalance;
     case CSSPropertyAlignItems:
         // FIXME: Per CSS alignment, this property should accept the same arguments as 'justify-self' so we should share its parsing code.
@@ -426,7 +424,6 @@ bool CSSParserFastPaths::isKeywordPropertyID(CSSPropertyID propertyId)
     case CSSPropertyWebkitColumnBreakBefore:
     case CSSPropertyWebkitColumnBreakInside:
     case CSSPropertyColumnFill:
-    case CSSPropertyWebkitColumnRuleStyle:
     case CSSPropertyFlexDirection:
     case CSSPropertyFlexWrap:
     case CSSPropertyFontKerning: