simplify classSet logic

[chrisirhc]

Remove a loop. className can be treated as a class itself.

• Add additional test for className containing only whitespace

[chrisirhc]

I don't think anybody should be relying on behavior on duplicate / de-duplicated classes though. Since it doesn't affect any behavior in the browser. The behavior is also inconsistent when there's multiple classes in a key in classSet.

But you're right, this does affect people who do rely on such (imho brittle) behavior.

[chrisirhc]

Simplified further thanks to @clanam .

[dawsbot]

Closing since this is stale. Feel free to re-open if this is still relevant and we can re-investigate.