message: fix an issue testing for dead iframes
diff: @@ -162,7 +162,7 @@ export default class ExtCommand {
  }, { frameId: top ? 0 : frameId }).then(r => {
  return r;
  }).catch(error => {
  - if (isReceivingEndError(error) && frameId && command !== "waitPreparation") {
  + if (this.isReceivingEndError(error) && frameId && command !== "waitPreparation") {
  return this.waitForFrameToRespond(command, target, value, implicitTime);
  }
  throw error;
  