Avoid to aria-hide the structure tree (bug 1894849)

[calixteman]

If one ancestor of the structure tree has the attribute aria-hidden then it's invisible for screen readers.

[Snuffleupagus]

Looking at the history that line was added PR #17790, as part of fixing bug 1881746. Since I don't really (at all) know a11y stuff, does removing this line (somehow?) re-introduce part of that bug or was it never actually a "necessary" change?

[calixteman]

I don't remember exactly why I added this aria-hidden (I wonder if it could just be a leftover after having tested if adding this attribute was helpful to fix the bug or not).
That said, I tested the patch on a mac with Firefox nightly and VO and it wfm.

[timvandermeij]

/botio integrationtest

[moz-tools-bot]

From: Bot.io (Linux m4)

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Received

Command cmd_integrationtest from @timvandermeij received. Current queue size: 0

Live output at: http://54.241.84.105:8877/6d35b58eb72a6b3/output.txt

[moz-tools-bot]

From: Bot.io (Windows)

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Received

Command cmd_integrationtest from @timvandermeij received. Current queue size: 0

Live output at: http://54.193.163.58:8877/6b1b998bf566abd/output.txt

[moz-tools-bot]

From: Bot.io (Linux m4)

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Success

Full output at http://54.241.84.105:8877/6d35b58eb72a6b3/output.txt

Total script time: 7.28 mins

• Integration Tests: Passed

[moz-tools-bot]

From: Bot.io (Windows)

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Success

Full output at http://54.193.163.58:8877/6b1b998bf566abd/output.txt

Total script time: 20.76 mins

• Integration Tests: Passed