Function sent (#5920)

* 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]

packages/babel-plugin-transform-function-sent/package.json

@@ -0,0 +1,18 @@
+{
+  "name": "babel-plugin-transform-function-sent",
+  "version": "7.0.0-alpha.15",
+  "description": "Compile the function.sent meta propety to valid ES2015 code",
+  "repository": "https://github.com/babel/babel/tree/master/packages/babel-plugin-transform-function-sent",
+  "license": "MIT",
+  "main": "lib/index.js",
+  "keywords": [
+    "babel-plugin"
+  ],
+  "dependencies": {
+    "babel-plugin-syntax-function-sent": "7.0.0-alpha.15",
+    "babel-helper-wrap-function": "7.0.0-alpha.15"
+  },
+  "devDependencies": {
+    "babel-helper-plugin-test-runner": "7.0.0-alpha.15"
+  }
+}