fix rest parameter array allocation loop being incorrectly aliased - fixes #1800

test/core/fixtures/transformation/es6.parameters.rest/async-function/actual.js

@@ -0,0 +1,7 @@
+var fn = async (...rest) => rest;
+
+var fn = async (...rest) => {
+  if (true) {
+    rest;
+  }
+};

test/core/fixtures/transformation/es6.parameters.rest/async-function/expected.js

@@ -0,0 +1,39 @@
+"use strict";
+
+var _this = this;
+
+var fn = function fn() {
+  for (var _len = arguments.length, rest = Array(_len), _key = 0; _key < _len; _key++) {
+    rest[_key] = arguments[_key];
+  }
+
+  return regeneratorRuntime.async(function fn$(context$1$0) {
+    while (1) switch (context$1$0.prev = context$1$0.next) {
+      case 0:
+        return context$1$0.abrupt("return", rest);
+
+      case 1:
+      case "end":
+        return context$1$0.stop();
+    }
+  }, null, _this);
+};
+
+var fn = function fn() {
+  for (var _len2 = arguments.length, rest = Array(_len2), _key2 = 0; _key2 < _len2; _key2++) {
+    rest[_key2] = arguments[_key2];
+  }
+
+  return regeneratorRuntime.async(function fn$(context$1$0) {
+    while (1) switch (context$1$0.prev = context$1$0.next) {
+      case 0:
+        if (true) {
+          rest;
+        }
+
+      case 1:
+      case "end":
+        return context$1$0.stop();
+    }
+  }, null, _this);
+};

test/core/fixtures/transformation/es6.parameters.rest/async-function/options.json

@@ -0,0 +1,3 @@
+{
+  "stage": 0
+}