Function updateTextNode

code/third-party/public/app.js:8242–8254

(returnFiber, current, textContent, expirationTime)

  }

  function updateTextNode(returnFiber, current, textContent, expirationTime) {
    if (current === null || current.tag !== HostText) {
      // Insert
      var created = createFiberFromText(textContent, returnFiber.mode, expirationTime);
      created['return'] = returnFiber;
      return created;
    } else {
      // Update
      var existing = useFiber(current, textContent, expirationTime);
      existing['return'] = returnFiber;
      return existing;
    }
  }

  function updateElement(returnFiber, current, element, expirationTime) {
    if (current !== null && current.type === element.type) {