Rename all proposal plugins to -proposal- from -transform- (#6570)

packages/babel-plugin-proposal-function-sent/test/fixtures/function-sent/multiple/expected.js

@@ -0,0 +1,13 @@
+function _skipFirstGeneratorNext(fn) { return function () { var it = fn.apply(this, arguments); it.next(); return it; }; }
+
+_skipFirstGeneratorNext(function* () {
+  let _functionSent = yield;
+
+  const a = _functionSent;
+  const b = _functionSent;
+  _functionSent = yield 4;
+  const c = _functionSent;
+  const d = _functionSent = yield;
+  const e = _functionSent;
+  return [a, b, c, d, e];
+})();