code: Node createAwait(JSType jsType, Node value) {
      Node result = IR.await(value);
      if (isAddingTypes()) {
        result.setJSType(checkNotNull(jsType));
      }
      return result;
    }
docs: Returns a new {@code await} expression.
  
  @param jsType Type we expect to get back after the await
  @param value value to await