anchor.diff:  
     /// An await is translated to an [awaitStatement].
     ///
  -  /// See the comments of [visitFun] for an example.
  +  /// See the comments of [rewriteFunction] for an example.
     @override
     js.Expression visitAwait(js.Await node) {
       assert(isAsync || isAsyncStar);
  
positive.code:     // Initialize names specific to the subclass.
      initializeNames();
  
      return node.accept(this);
    }
  
    js.Expression get currentErrorHandler {
  
negative.code:     return result.reversed.toList();
    }
  
    /// See the comments of [rewriteFunction] for more explanation.
    void visitTry(js.Try node) {
      if (!shouldTransform(node)) {
        js.Block body = translateInBlock(node.body);
  