Yes, the output is uglier. But, this is necessary for me to refactor
`replaceSupers` for #7733, which is necessary for both #7555 and
https://github.com/babel/babel/pull/7553#issuecomment-381434519.
I'm still in the middle of cleaning up all this code. Don't expect
`transformClass` to survive much longer as it's written currently.
* #7349
- Add "use strict" directive to transformed class bodies
* Update tests (#7349)
* Add test for program with use strict directive (#7349)
* Update tests (#7349)
* Update source mapping (#7349)
* Add test for parent blockStatement with use strict directive (#7349)
* Update tests (#7349)
* Update tests (#7349)
* Update tests (#7349)
* Add test for constructor-only class (#7349)
* Constructor only classes are strict, too
But constructor only that use non-simple parameters must use a strict function wrapper.
* Fix test
* Wrapper not needed if class is already strict
* Revert change to lerna.json
