aebb8534f3
We have a number of base-classes that are only intended to be extended, but never to be used directly. To help enforce this during development these base-class constructors will check for direct usage, however that code is obviously not needed in the actual builds. *Note:* This patch reduces the size of the `gulp mozcentral` output by `~2.7` kilo-bytes, which isn't a lot but still cannot hurt.