Tags in the webvtt subtitle are not parsed

[Peterdoo]

Have you read the FAQ and checked for duplicate open issues?
YES

What version of Shaka Player are you using?
v4.3.4-uncompiled

Can you reproduce the issue with our latest release version?
YES

Can you reproduce the issue with the latest code from main?

Are you using the demo app or your own custom app?
Demo app shaka-player-demo.appspot.com

If custom app, can you reproduce the issue using our demo app?

What browser and OS are you using?
Chrome Version 109.0.5414.120 (Official Build) (64-bit) on Win11

For embedded devices (smart TVs, etc.), what model and firmware version are you using?

What are the manifest and license server URIs?

What configuration are you using? What is the output of player.getConfiguration()?

Demo app shaka-player-demo.appspot.com

What did you do?

Played a HLS video with the following cue in the webvtt file:
10:00:00.000 --> 10:00:04.000 line:90%,end position:50%
First line is <u>underlined </u>and left positioned.
Second line is <i>italic </i>&amp; moved right.
Third line is right justified and unjustif.

What did you expect to happen?
The tags should have been parsed. The two words inside the spans should be displayed underlined or italic.

What actually happened?

Tags stayed unparsed. The tags were displayed as text instead of being parsed and using them for text formatting.

This is how it looks like:

[avelad]

@Peterdoo I created #4960