CSS animations cause high cpu

[programmin]

Animations such as those on

.wpview-loading ins

cause high cpu (>50percent of one on my i5)

If I replace "linear" with, say, "steps(12)" it goes down to a reasonable cpu load.

[azaozz]

12 steps seems too choppy. Tried 36 and shortening the ins a bit. That reduced the CPU usage here by more than half: was 8-9 now is 3-4, GPU at 1-2 as reported by Chrome's task manager, 5 years old i5).

[azaozz]

In 36976:

TinyMCE: tweak the small animation shown while waiting for wpView data to make it sell CPU intensive.

Props programmin.
Fixes #33525.