Accessibility regression: The block contenteditable aria-multiline value is now an empty string

[afercia]

Describe the bug

See #19124 (comment)

In #23132 the default value for the aria-multiline attribute set to the blocks contenteditable was changed to empty string.

This attribute needs an explicit true string value so that is rendered as aria-multiline="true". This was discussed long time ago, as there was some overlapping in the way the related prop was used. The issue was clarified at WordCamp US Nashville 2017. The implementation is now changed, not sure why.

Worth reminding once again that this attribute is only meant to be used for assistive technologies. Amongst other things, a true value allows screen readers to differentiate between a textbox role meant as equivalent of an input field, and a textbox role that needs to be perceived as a textarea element instead.

More details: https://www.w3.org/TR/wai-aria-1.1/#aria-multiline

Screenshots to clarify, testing with Safari + VoiceOver:

With an empty value aria-multiline="", the block is announced as "text field":

With a value aria-multiline="true", the block is announced as "textarea":

I'm not sure if the related prop is still used internally also for other purposes. Regardless, what is needed for accessibility is that all the contenteditable elements (with the exceptions that were already implemented before the recent refactoring) have a non-empty aria-multiline attribute. The value needs to be set to true.

/Cc @ellatrix @youknowriad

[ellatrix]

Thanks for the report! Seems to have been removed accidentally.