message: fix discrete animation
diff: @@ -379,12 +379,12 @@ class Track {
  const lastKf = kfs[kfsLen - 1];
  const isDiscrete = this.discrete;
  - if (!isDiscrete) {
  for (let i = 0; i < kfsLen; i++) {
  const kf = kfs[i];
  const value = kf.value;
  const lastValue = lastKf.value;
  kf.percent = kf.time / maxTime;
  + if (!isDiscrete) {
  if (arrDim > 0 && i !== kfsLen - 1) {
  // Align array with target frame.
  fillArray(value as NumberArray, lastValue as NumberArray, arrDim);
  