unicode/bidi Fix bracket matching

[pgundlach]

This fixes golang/go/issues/#72089

The test itself is not correct, it misses the fix from golang/go/issues/71809

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[gopherbot]

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[gopherbot]

Message from Gopher Robot:

Patch Set 1:

(1 comment)

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[gopherbot]

This PR (HEAD: fb21995) has been imported to Gerrit for code review.

Please visit Gerrit at https://go-review.googlesource.com/c/text/+/655458.

Important tips:

• Don't comment on this PR. All discussion takes place in Gerrit.
• You need a Gmail or other Google account to log in to Gerrit.
• To change your code in response to feedback:
  • Push a new commit to the branch used by your GitHub PR.
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[gopherbot]

Message from Patrick Gundlach:

Patch Set 2:

(2 comments)

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