clarify ImageTrack repetition count

[tnikkel]

repetition count is listed as "The number of times the animation is intended to repeat."

This seems like it is intended to mean that "repetition count" = 1 means the animation plays through a total of two times, "repetition count" = 0 means the animation plays through a total of one time. It would be good to get that clearly worded in the spec as one could alternatively interpret it as one repetition means one total play through of the animation that has been recorded in the file.

[dalecurtis]

  // The image's preferred repetition count. Zero means play through only once,
  // a value of N means play N + 1 times. Infinity means play forever.

Here's the comment from the IDL file: https://source.chromium.org/chromium/chromium/src/+/main:third_party/blink/renderer/modules/webcodecs/image_track.idl;l=20;drc=4af99b12567f1e9072640103e361f0f0df9d9a12

I can add some clarifying text to make this clearer though.

[tnikkel]

Is that idl file available somewhere outside of the chromium repo? When I'm looking at specs I'm not going to the chromium repo. The corresponding idl in the Firefox repo doesn't have a comment https://searchfox.org/firefox-main/rev/dab03896ede1413be148884e054b311767bcf1a0/dom/webidl/ImageDecoder.webidl#41

[chrisn]

Adding some clarifying text SGTM.

[dalecurtis]

No the idl file is only in Chromium, I just linked it as documentation of my initial thought process when this feature was added. We should clarify in the actual spec.