The Firefox addon currently fails with:
```
SyntaxError: missing ; before statement pdf.js:1692:12
TypeError: PDFJS.shadow is not a function viewer.js:6228:12
```
The test case was changed in 1faca19021 because the original file was not available anymore. However, its hash was also changed, meaning that we do not test the intended version anymore.
This patch makes sure that we test the intented version by reverting to
the original hash and using a link, also pointing to the Internet
Archive, with the original file.
This test was disabled in PR 4732, because the file was no longer available. The motivation being that there were two other files which should be good replacements. However, one of those has since been replaced with a reduced test-case (which doesn't exercise the same code-path), and in the other one the error does not appear to be entirely identical.
Hence it seems reasonable to re-add the 'aboutstacks.pdf' test, since it was possible to find it on the Internet Archive (by searching using a different URL, compared to the current one).
Issue 6854 - Update the link locations to point to the Internet Archive for tests: 20130226130259, JST2007-5, P020121130574743273239, SFAA_Japanese, TaroUTR50SortedList112
Note that despite the new file having a different hash than the the current one, it does render *identically* and most importantly it uses *the same* JBIG2 functionality.
For reference, please see issue 3666 and PR 3738.
*This patch follows a similar idea as PR 5756.*
The patch is based on the nice debugging done by Brendan in the referenced issue 6782.
A better way to handle this, and similar issues, would probably be to completely ignore what the PDF file claims about font type/subtype, and just check the actual data. But until that kind of rewrite happens, this patch should help.
Fixes 6782.
When generating new references locally on Windows, after PR 6724, I get the following output:
```
WARNING: Unable to open file for reading "Error: ENOENT, open 'c:\Users\Jonas\Git\pdfjs\test\pdfs\issue_3694_reduced.pdf'".
Unable to verify the checksum for the files that are used for testing.
Please re-download the files, or adjust the MD5 checksum in the manifest for the files listed above.
```
Compared to the name of the file (`issue3694_reduced.pdf`), you see that the manifest entry has a superfluous underscore in the "file" entry.
Apparently some PDF files can have annotations with `URI` entries ending with `null` characters, thus breaking the links.
To handle this edge-case of bad PDFs, this patch moves the already existing utility function from `ui_utils.js` into `util.js`, in order to fix those URLs.
Fixes 6832.
Jonas Jenwald
Tim van der Meij
Brendan Dahl
Yury Delendik
Daan Sprenkels