Move array reference into for head initializer (#9698)

* Move array reference into for head initializer

* Update packages/babel-plugin-transform-for-of/src/index.js

Co-Authored-By: danez <daniel@tschinder.de>

* Fix tests

packages/babel-core/test/fixtures/transformation/misc/regression-1169/output.js

@@ -1,10 +1,9 @@
 function foo() {
   var input = ['a', 'b', 'c'];
   var output = {};
-  var _arr = input;
 
-  for (var _i = 0; _i < _arr.length; _i++) {
-    var c = _arr[_i];
+  for (var _i = 0, _input = input; _i < _input.length; _i++) {
+    var c = _input[_i];
     var name = c;
     output[name] = name;
   }