bug#45955: So-long mode did not swoop down and rescue me today

[積丹尼 Dan Jacobson]

So-long mode did not swoop down and rescue me today (despite my setting
in https://www.jidanni.org/comp/configuration/.emacs .)
1. $BROWSER https://www.taipower.com.tw/
2. CTRL+S Save webpage complete
3. file base.js
base.js: ASCII text, with very long lines
4. wc base.js
   8790   33165 1556387 base.js
5. emacs base.js
 C-v                    ;; scroll-up-command (hit 20 of these, then finally 
<end>,)
 <end>                  ;; end-of-buffer

Emacs got stuck.
Banging on the keyboard didn't help.
The CPU meter turned red.
Ah, go back to the shell and suspend (fg, CTRL+Z) emacs.
OK, now start it again, in the foreground: fg, or background: bg.
Finally emacs is accepting my CTRL+G's again.

Conclusion: hosed emacs again with such a javascript file.
emacs-version "27.1"