Describe the bug
Automatic word wrap doesn't work on plain text files. View->Page Style->Wrap Long Lines does nothing.
To Reproduce
Example for testing:
https://pastebin.com/raw/pyNW8ZkM
Expected behavior
Firefox 56:

What I get
Waterfox 56.2.3-56.2.4 new profile:

Desktop:
Additional Information
Word wrap on Firefox 56 only works for ANSI and UTF-8, if file is in UTF-16 it doesn't work. (Tested on local files)
I also see this bug. This message in Browser Console seems related -
Security Error: Content at https://pastebin.com/raw/pyNW8ZkM may not load or link to resource://gre-resources/plaintext.css.
Looks like it's this bug:
https://bugzilla.mozilla.org/show_bug.cgi?id=1395486
…
Example for testing:
https://pastebin.com/raw/pyNW8ZkM
…
Waterfox 56.2.3-56.2.4 new profile:
…
- OS: Windows 7 x64, Windows 10 x64
…
Not bugged for me with 56.2.3 on FreeBSD:

Also not bugged with a different profile in safe mode.
@grahamperrin That's because FreeBSD build already includes the patch: https://svnweb.freebsd.org/ports/head/www/waterfox/files/patch-bug1395486?revision=466694&view=markup&pathrev=480899
Hurrah so that's one step closer to a PR. G'wan, anybody, g'wan …
Most helpful comment
@grahamperrin That's because FreeBSD build already includes the patch: https://svnweb.freebsd.org/ports/head/www/waterfox/files/patch-bug1395486?revision=466694&view=markup&pathrev=480899