DevTools: do not make main panel unconditionally focused by default.

third_party/WebKit/Source/devtools/front_end/main/SimpleApp.js

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 /**
  * @implements {Common.App}
  * @unrestricted
  */
 Main.SimpleApp = class {
   /**
    * @override
    * @param {!Document} document
    */
   presentUI(document) {
     var rootView = new UI.RootView();
     UI.inspectorView.show(rootView.element);
     rootView.attachToDocument(document);
+    rootView.focus();
   }
 };
 
 /**
  * @implements {Common.AppProvider}
  * @unrestricted
  */
 Main.SimpleAppProvider = class {
   /**
    * @override
    * @return {!Common.App}
    */
   createApp() {
     return new Main.SimpleApp();
   }
 };