text: //// [for-of25.ts]
  class StringIterator {
      [Symbol.iterator]() {
          return x;
      }
  }
  
  var x: any;
  for (var v of new StringIterator) { }
  
  //// [for-of25.js]
  class StringIterator {
      [Symbol.iterator]() {
          return x;
      }
  }
  var x;
  for (var v of new StringIterator) { }
  