[css-animations-2] frames() as a more intuitive steps() about csswg-drafts

[birtles]

I'm planning to spec this in Web Animations: https://w3c.github.io/web-animations/#issue-fc1dd2fc

[katzlbt]

If you do want to see both the starting and ending values, and have a stepped transition between them, you need to do some math and overshoot the desired end-point instead.

I do not agree with this. In the case of animating a sprite-sheet with finite iterations (background-position) it is impossible to overshoot due to the limitations of the underlying background-image. I think that possible parametrizations to animate all frames correctly with fill-mode forwards only exist for 1 and infinite iterations. Run the example here: http://stackoverflow.com/questions/38809527/css-spritesheet-animation-fill-mode-forwards-with-steps-ends-on-wrong-position

Should this be a separate issue?
I think this is not an issue of intuitiveness. It appears to be uncharted territory in the specs, if not a specs-bug.
Is there a link to a draft for the proposed frames() timing-function?

[tabatkins]

Resolved now (we're using steps(), but adding a keyword with the behavior described here). Closing in favor of #1680 to track remaining naming issue.