bug#44214: 28.0.50; css-mode: no completion in declaration with newline after

[Dmitry Gutov]

X-Debbugs-CC: Simen Heggestøyl <simenheg@gmail.com>

1. Create new buffer (or switch to scratch), then M-x css-mode.
2. Replace the contents with the following:

div {
  transform:
    rota

3. Move the point to the end of 'rota' and type C-M-i.

4. See no completions.

If there is no newline after the colon, before the attribute value,
C-M-i does perform completion.

Originally reported in 
https://github.com/company-mode/company-mode/issues/1029

In GNU Emacs 28.0.50 (build 1, x86_64-pc-linux-gnu, GTK+ Version 
3.24.20, cairo version 1.16.0)
 of 2020-10-11 built on potemkin
Repository revision: c66165b5c08e12c5dcf494fea42e61df693b80b9
Repository branch: master
Windowing system distributor 'The X.Org Foundation', version 11.0.12008000
System Description: Ubuntu 20.04.1 LTS