As described in the issue, having a DOM element with `id=page2` (or any other number) will automatically cause that element to become linkable through the URL hash. That's currently leading to some confusing and outright wrong behaviour, since it obviously only works for pages that have been loaded and rendered.
For PDF documents the only officially supported way to reference a particular page through the URL hash is using the `#page=2` format, which also works for all pages regardless if they're loaded or not.
As far as I can tell there's nothing in the PDF.js default viewer that actually depends on the page/thumbnail `id` at this point in time, hence why I believe that this removal ought to be safe.
Just as a pre-caution this patch adds an `aria-label` to the page canvas, similar to the thumbnail canvas/image, to at least keep this information in the DOM.
Most of the files in this folder (except for the en-US folder) have been
imported from the Firefox Nightly branch;
please see https://hg.mozilla.org/l10n-central. Some of the files are
licensed under the MPL license. You can obtain a copy of the license at
https://mozilla.org/MPL/2.0.
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