Enable/Unprefix Animations & Transitions, add basic tests

sky/engine/core/css/parser/CSSGrammar.y

Index: sky/engine/core/css/parser/CSSGrammar.y
diff --git a/sky/engine/core/css/parser/CSSGrammar.y b/sky/engine/core/css/parser/CSSGrammar.y
index 86f8c6f085ea2f5387b3a9e0804a27ccdf6f28d8..154fc8941c00b3b0ef6830a97faf43624d93febc 100644
--- a/sky/engine/core/css/parser/CSSGrammar.y
+++ b/sky/engine/core/css/parser/CSSGrammar.y
@@ -187,7 +187,6 @@ inline static CSSParserValue makeIdentValue(CSSParserString string)
 %token INTERNAL_KEYFRAME_KEY_LIST_SYM
 %token INTERNAL_SUPPORTS_CONDITION_SYM
 %token KEYFRAMES_SYM
-%token WEBKIT_KEYFRAMES_SYM
 
 %token ATKEYWORD
 
@@ -741,9 +740,6 @@ keyframes_rule_start:
     before_keyframes_rule KEYFRAMES_SYM maybe_space {
         $$ = false;
     }
-  | before_keyframes_rule WEBKIT_KEYFRAMES_SYM maybe_space {
-        $$ = true;
-    }
     ;
 
 keyframes: