fix: keyframe names are ordered

[whisk]

Description

Ocassionally keyframes were out of order. Yesterday I got this error in the PR pipeline:

"[.] @keyframes anim_5c67ab5b65 { to { color: blue; } from { color: red; } } [...]" 
does not contain "@keyframes anim_5c67ab5b65 { from { color: red; } to { color: blue; } }"

Test:       	TestGenerateCSS

I wonder why this didn't happen more often.

Fix

sortedKeys, and I made it accept generic maps.

[chasefleming]

Thanks for catching this!