Remove application of tts:unicodeBidi to tt:p element.

[nigelmegitt]

Arising from #1211 clarify the application of unicodeBidi and direction on the p element (only).

Suggest matching CSS text direction.

• direction sets the paragraph embedding level
• unicodeBidi values plaintext and bidi-override have specific effects
• other values have no specific effect

[palemieux]

direction sets the paragraph embedding level

@nigelmegitt To make sure, the idea is that tts:direction sets the paragraph embedding level in addition to potentially altering the inline progression direction per #1213.

unicodeBidi values plaintext and bidi-override have specific effects
other values have no specific effect

@nigelmegitt What is the intent of the above if tts:unicodeBidi does not apply to p?

[nigelmegitt]

direction sets the paragraph embedding level

@nigelmegitt To make sure, the idea is that tts:direction sets the paragraph embedding level in addition to potentially altering the inline progression direction per #1213.

Altering the inline progression direction is in addition, but yes, I think this is what we intended.

unicodeBidi values plaintext and bidi-override have specific effects
other values have no specific effect

@nigelmegitt What is the intent of the above if tts:unicodeBidi does not apply to p?

Hmm, I'm not sure about that now. We created this issue jointly during the call and nobody called this out! @fantasai can you recall?

[palemieux]

@nigelmegitt It looks like bidiOverride has an effect on p: https://www.w3.org/TR/css-writing-modes-4/#unicode-bidi

[palemieux]

See discussion at #1214 (comment)