(Resolved) Drop 'default' from 'switch type'

[jeffdyer]

argument 1, experience indicates that it is often clearer to say

    case (x:*) { }

when you mean

    default { }

argument 2, we try to avoid two ways to say the same thing.

argument 3, the implementation is awkward because there is no binding.

[graydon]

fine by me

[lth]

Jeff, pls close when you've merged this into the grammar.