I made some mistakes when trying to make the content_disposition.js
compatible with non-modern browsers (IE/Edge).
Notably, text decoding was usually skipped because of the inverted
logical check at the top of `textdecode`.
I verified that this new version works as expected, as follows:
1. Visit 55c71eb44e/test/
and get test-content-disposition.js
also get test-content-disposition.node.js if using Node.js,
or get test-content-disposition.html if you use a browser.
2. Modify `test-content-disposition.node.js` (or the HTML file) and
change `../extension/content-disposition.js` to `PDFJS-content_disposition.js`
3. Copy the `getFilenameFromContentDispositionHeader` function from
`content_disposition.js` (i.e. the file without the trailing exports)
and save it as `PDFJS-content_disposition.js`.
4. Run the tests (`node test-content-disposition.node.js` or by opening
`test-content-disposition.html` in a browser).
5. Confirm that there are no failures: "Finished all tests (0 failures)"
The code has a best-efforts fallback for Microsoft Edge, which lacks the
TextDecoder API. The fallback only supports the common UTF-8 encoding.
To simulate this in a test, modify `PDFJS-content_disposition.js` and
deliberately throw an error before `new TextDecoder`. There will be two
failures because we don't want to include too much code to support text
decoding for non-UTF-8 encodings in Edge
```
test-content-disposition.js:265 Assertion failed: Input: attachment; filename*=ISO-8859-1''%c3%a4
Expected: "ä"
Actual : "ä"
test-content-disposition.js:268 Assertion failed: Input: attachment; filename*=ISO-8859-1''%e2%82%ac
Expected: "€"
Actual : "€"
```
