Throws: oldIE native Error types, remove String

Handle oldIE native Error types in `throws`.
Remove the String comparison type from `throws`.

Fixes #547.
Closes #579.
Closes #593.

Related to jquery/api.qunitjs.com#54.
Hm.. I don't like instantiating anything from within here, especially playing with input. Is there some other way we can determine whether it inherits from Error?