1880097 - datetime input does not use "dir" of web exposed locale

Status: NEW

(Toolkit :: UI Widgets, defect, P3)

Description

[Henry Wilkes (they/them) [:henry-x]]

Noticed when testing in Tor Browser.

Steps to reproduce

Using Firefox with "ar" locale:

1. In "about:config" set privacy.spoof_english to 2.
2. Restart.
3. Visit https://developer.mozilla.org/en-US/docs/Web/HTML/Element/input/datetime-local#basic_uses_of_datetime-local

Result

From left to right, the unfilled datetime input shows: picker; AM/PM input; date input; time input.

After entering an hour, the layout switches to: picker; date input; time input; AM/PM input.

Expect

The order and direction should remain the same and follow the spoofed en-US direction: date input; time input; AM/PM input; picker.

Note, the fact that the placeholders use "ar" rather an "en-US" is a separate issue: bug#1880108.

Cause

I think the problem is that datetime input uses the app locale direction to set the "dir" attribute. Rather than using the direction associated with the mLocales[0].