
Steps 4-10 of https://www.w3.org/TR/webvtt1/#cue-computed-line This part is harder to fit into our code structure because it depends on how many cues are simultaneously visible - so it has to go in WebvttSubtitle not WebvttCueParser (which only deals with individual cues in isolation). This removes the `isNormal()` method that was trying to approximate the correct behaviour. PiperOrigin-RevId: 309021686