* Create "babel-helper-wrap-function"
It contains the logic to wrap a function inside a call expression.
It was part of the "babel-helper-remap-async-to-generator" package, but
it is needed to transpile "function.sent"
* Create "babel-transform-function-sent"
It transforms the "function.sent" meta property by replacing it with
"yield" and making the generator ignore the first ".next()" call.
* "function.sent" is the last value passed to .next(), not the first one
* Disable exec tests on old node
* Fix flow error
* Add "transform-function-sent" to "stage-2" preset
* Do every trasformation in one traversal
* Test for "yield function.sent"
* [skip ci]
* Fix some typos [skip ci]
