remove CSS 'all' property.

sky/engine/core/css/CSSComputedStyleDeclaration.cpp

Index: sky/engine/core/css/CSSComputedStyleDeclaration.cpp
diff --git a/sky/engine/core/css/CSSComputedStyleDeclaration.cpp b/sky/engine/core/css/CSSComputedStyleDeclaration.cpp
index df95d1be9e3e7a3dbda69d727b44259bd9fabb55..f1bc1a37dbc8ef0ec5dc905eb5b67e31b475a594 100644
--- a/sky/engine/core/css/CSSComputedStyleDeclaration.cpp
+++ b/sky/engine/core/css/CSSComputedStyleDeclaration.cpp
@@ -2137,9 +2137,6 @@ PassRefPtr<CSSValue> CSSComputedStyleDeclaration::getPropertyCSSValue(CSSPropert
         /* @viewport rule properties */
         case CSSPropertyOrientation:
             break;
-
-        case CSSPropertyAll:
-            return nullptr;
     }
 
     logUnimplementedPropertyID(propertyID);