Fix IE8 disabled input throwing on focus

When IE8 focuses a disabled item, it throws
This makes sure the we're not focusing the item during selection restoration/autofocus when the element's disabled.

src/browser/ReactInputSelection.js

@@ -21,6 +21,7 @@
 var ReactDOMSelection = require('ReactDOMSelection');
 
 var containsNode = require('containsNode');
+var focusNode = require('focusNode');
 var getActiveElement = require('getActiveElement');
 
 function isInDocument(node) {
@@ -71,7 +72,7 @@ var ReactInputSelection = {
           priorSelectionRange
         );
       }
-      priorFocusedElem.focus();
+      focusNode(priorFocusedElem);
     }
   },
 

src/browser/dom/components/AutoFocusMixin.js

@@ -19,10 +19,12 @@
 
 "use strict";
 
+var focusNode = require('focusNode');
+
 var AutoFocusMixin = {
   componentDidMount: function() {
     if (this.props.autoFocus) {
-      this.getDOMNode().focus();
+      focusNode(this.getDOMNode());
     }
   }
 };