bug#29159: 27.0.50; Hang in HTML/CSS code

[Lars Ingebrigtsen]

If I put the following into a file called foo.html:

<style>
@keyframes dropFlowParticles {
  0% { background-position: 0 0, 0 0, 30px 40px, 0 0, 10px 0; }
}
</style>

End then delete the 0%, and then start typing "top", then Emacs will
hang kinda hard.  A C-g will eventually break out and the "t" will be
inserted, but then Emacs hangs again.

Setting debug-on-quit doesn't give me a backtrace, so I'm not sure where
it's hanging.


In GNU Emacs 27.0.50 (build 4, x86_64-pc-linux-gnu, GTK+ Version 3.22.11)
 of 2017-11-03 built on mouse
Repository revision: 620247ac205b80ceb142ee70500ab2c3ffa46fe2
Windowing system distributor 'The X.Org Foundation', version 11.0.11903000
System Description:     Ubuntu 17.04


-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no