Making shadow declarations consistent between elevations 0 and 24.

[sgomes]

Also adds missing elevations.

@Garbee or @surma: PTAL!

[Garbee]

Where are these missing elevations specified for use/construction? I don't recall ever seeing where they are necessary somehow. We shouldn't include extra things like this without a clear use-case imo. It isn't keeping things lite.

Also, 0dp... Isn't that just box-shadow:none;? Where does adding this one in particular provide benefit?

[sgomes]

We're adding the different elevations due to guidance from the MD team. Apparently, they should all be available, even though only a few examples are shown on the spec. They provided an algorithm to calculate the intermediate elevation values, as well as the full output of running that algorithm, which I used to create all the mixins.

You're right about the 0dp elevation; the numbers there were to make the calculation easier, but implementation-wise it makes more sense to have it as none. Made that change.

[Garbee]

AH ok, thanks for explaining why they are needed.

LGTM.

[sgomes]

Thanks, @Garbee!