Remove even more @keyframes related code.

sky/engine/core/css/StyleRule.cpp

Index: sky/engine/core/css/StyleRule.cpp
diff --git a/sky/engine/core/css/StyleRule.cpp b/sky/engine/core/css/StyleRule.cpp
index f5d70f294057a4ca52f75c0a499d886b7643f916..77b4e5ead8cebf30bf91133dd301c1d4ed328572 100644
--- a/sky/engine/core/css/StyleRule.cpp
+++ b/sky/engine/core/css/StyleRule.cpp
@@ -23,7 +23,6 @@
 #include "sky/engine/core/css/StyleRule.h"
 
 #include "sky/engine/core/css/StylePropertySet.h"
-#include "sky/engine/core/css/StyleRuleKeyframes.h"
 
 namespace blink {
 
@@ -45,9 +44,6 @@ void StyleRuleBase::destroy()
     case Supports:
         delete toStyleRuleSupports(this);
         return;
-    case Keyframes:
-        delete toStyleRuleKeyframes(this);
-        return;
     case Unknown:
         ASSERT_NOT_REACHED();
         return;