function instantiateChild(childInstances, child, name, selfDebugID) {
	  // We found a component instance.
	  var keyUnique = childInstances[name] === undefined;
	  if (process.env.NODE_ENV !== 'production') {
	    if (!ReactComponentTreeHook) {
	      ReactComponentTreeHook = __webpack_require__(28);
	    }
	    if (!keyUnique) {
	      process.env.NODE_ENV !== 'production' ? warning(false, 'flattenChildren(...): Encountered two children with the same key, ' + '`%s`. Child keys must be unique; when two children share a key, only ' + 'the first child will be used.%s', KeyEscapeUtils.unescape(name), ReactComponentTreeHook.getStackAddendumByID(selfDebugID)) : void 0;
	    }
	  }
	  if (child != null && keyUnique) {
	    childInstances[name] = instantiateReactComponent(child, true);
	  }
	}
ReactChildReconciler provides helpers for initializing or updating a set of
children. Its output is suitable for passing it onto ReactMultiChild which
does diffed reordering and insertion.