Remove backface visibility

sky/engine/core/css/parser/BisonCSSParser-in.cpp

Index: sky/engine/core/css/parser/BisonCSSParser-in.cpp
diff --git a/sky/engine/core/css/parser/BisonCSSParser-in.cpp b/sky/engine/core/css/parser/BisonCSSParser-in.cpp
index 7eb9ef41af689058cf27ae48a857bcef25c1dd2a..e2053b3bded21e6d1297eaf582a905e2a1ce0d8e 100644
--- a/sky/engine/core/css/parser/BisonCSSParser-in.cpp
+++ b/sky/engine/core/css/parser/BisonCSSParser-in.cpp
@@ -385,9 +385,6 @@ bool isValidKeywordPropertyAndValue(CSSPropertyID propertyId, CSSValueID valueID
     case CSSPropertyTouchActionDelay: // none | script
         ASSERT(RuntimeEnabledFeatures::cssTouchActionDelayEnabled());
         return valueID == CSSValueScript || valueID == CSSValueNone;
-    case CSSPropertyBackfaceVisibility:
-    case CSSPropertyWebkitBackfaceVisibility:
-        return valueID == CSSValueVisible || valueID == CSSValueHidden;
     case CSSPropertyWebkitBoxDecorationBreak:
         return valueID == CSSValueClone || valueID == CSSValueSlice;
     case CSSPropertyAlignContent:
@@ -465,8 +462,6 @@ bool isKeywordPropertyID(CSSPropertyID propertyId)
     case CSSPropertyTextRendering:
     case CSSPropertyTouchActionDelay:
     case CSSPropertyUnicodeBidi:
-    case CSSPropertyBackfaceVisibility:
-    case CSSPropertyWebkitBackfaceVisibility:
     case CSSPropertyWebkitBorderAfterStyle:
     case CSSPropertyWebkitBorderBeforeStyle:
     case CSSPropertyWebkitBorderEndStyle: