clearing skottie canvas on every frame

images/js/screenshot_skottie.js

diff --git a/images/js/screenshot_skottie.js b/images/js/screenshot_skottie.js
index b7218cc..8942cc1 100644
--- a/images/js/screenshot_skottie.js
+++ b/images/js/screenshot_skottie.js
@@ -44,6 +44,7 @@
       animationData.w * devicePixelRatio,
       animationData.h * devicePixelRatio,
     );
+    skcanvas.clear(canvasKit.Color(0, 0, 0, 0.0));
     animation.render(skcanvas, bounds);
     surface.flush();
   };