Remove IE8-specific focus polyfill (#11800)

packages/react-dom/src/client/ReactInputSelection.js

@@ -6,7 +6,6 @@
  */
 
 import containsNode from 'fbjs/lib/containsNode';
-import focusNode from 'fbjs/lib/focusNode';
 import getActiveElement from 'fbjs/lib/getActiveElement';
 
 import * as ReactDOMSelection from './ReactDOMSelection';
@@ -70,7 +69,7 @@ export function restoreSelection(priorSelectionInformation) {
       }
     }
 
-    focusNode(priorFocusedElem);
+    priorFocusedElem.focus();
 
     for (let i = 0; i < ancestors.length; i++) {
       const info = ancestors[i];