fix syntax

tests/animation.ce

@@ -2,20 +2,22 @@
 var Anim = (() => {
   def DEFAULT_MIN = 1 / 60;           /* 16 ms – one frame */
 
-  function play(source, loop=true){
+  function play(source, loop){
+    var local_loop = !is_null(loop) ? loop : (!is_null(source.loop) ? source.loop : true);
     return {
       src   : source,
       idx   : 0,
       timer : 0,
-      loop  : loop ?? source.loop ?? true
+      loop  : local_loop
     };
   }
 
   function update(a, dt){
     a.timer += dt;
-    def frames = a.src.frames;
+    var frames = a.src.frames;
+    var time = null;
     while(true){
-      def time = max(frames[a.idx].time || 0, Anim.minDelay);
+      time = max(frames[a.idx].time || 0, Anim.minDelay);
       if(a.timer < time) break;        /* still on current frame */
 
       a.timer -= time;