Function useFiber

lib/assets/react-source/development/react.js:17195–17202

(fiber, pendingProps)

	  }

	  function useFiber(fiber, pendingProps) {
	    // We currently set sibling to null and index to 0 here because it is easy
	    // to forget to do before returning it. E.g. for the single child case.
	    var clone = createWorkInProgress(fiber, pendingProps);
	    clone.index = 0;
	    clone.sibling = null;
	    return clone;
	  }

	  function placeChild(newFiber, lastPlacedIndex, newIndex) {
	    newFiber.index = newIndex;