XSS attribute handling mangles valid attribute names containing numbers (D7 backport)

I am uploading a new patch - reroll & removed the plus signs not present in the D10.

Now the patch should be equal to the current D10 code: https://git.drupalcode.org/project/drupal/-/blob/11.x/core/lib/Drupal/Component/Utility/Xss.php#L216

Adding also test only patch to see that the attrbutes are malformed in the current state.

The last submitted patch, 4: 2847553-4_test-only.patch, failed testing. View results →

Adding a tag for the review from another D7 maintainer before commit.

Thanks; great that we added a test.

Automatically closed - issue fixed for 2 weeks with no activity.