Unprefixed `text-size-adjust`

[BenjaminAster]

Description

The text-size-adjust CSS property still needs a -webkit- prefix in WebKit and Firefox. (Firefox additionally supports the -moz- prefix.)

WebKit seems to already match the behavior (?) (see bug) while Firefox does not yet implement percentages (see bug). Personally though I think not supporting percentages should not block unprefixing since the most common usage of text-size-adjust probably is setting it to none anyway, and there probably isn't any compatibility risk with user agents supporting only a subset of a property's valid value syntaxes.

---

This issue is one of seven issues regarding unprefixing CSS properties/values, originally all in #702 (as per https://github.com/web-platform-tests/interop/issues/702#issuecomment-2358173009). The aim is to group the properties together into multiple (but not seven) focus areas.

Specification

https://drafts.csswg.org/css-size-adjust-1/#adjustment-control

Additional Signals

No response