Use foldr instead of foldl and reverse in Html.Styled.Internal

[ahstro]

Instead of using List.foldl to reduce children and then having to List.reverse the child nodes, use List.foldr and skip reversing.

I think this makes sense, since Dicts (the other thing being accumulated with the fold*) are often stated as a valid to use when order is irrelevant. I suppose there might be some potential problem if the order of the Dict is actually relied upon to order the styles properly (them being cascading and all). The example page looks the same after this change, but it's not very complex, so the likelihood of styles conflicting based on order is minimal.

[rtfeldman]

@ahstro I'm concerned that this would actually cause a regression instead of working as intended 😅 - do you think you could add a test case demonstrating that it still works properly?