Consider slots' tabindex in focus navigation

third_party/WebKit/Source/core/page/FocusController.cpp

 /*
  * Copyright (C) 2006, 2007 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Nuanti Ltd.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 319 matching lines @@
     return isNonKeyboardFocusableShadowHost(element) || isShadowInsertionPointFocusScopeOwner(element) || isHTMLSlotElement(element);
 }
 
 inline bool isShadowHostDelegatesFocus(const Element& element)
 {
     return element.authorShadowRoot() && element.authorShadowRoot()->delegatesFocus();
 }
 
 inline int adjustedTabIndex(Element& element)
 {
-    return isNonFocusableFocusScopeOwner(element) ? 0 : element.tabIndex();
+    return (isNonKeyboardFocusableShadowHost(element) || isShadowInsertionPointFocusScopeOwner(element)) ? 0 : element.tabIndex();
 }
 
 inline bool shouldVisit(Element& element)
 {
     return element.isKeyboardFocusable() || isNonFocusableFocusScopeOwner(element);
 }
 
 Element* findElementWithExactTabIndex(ScopedFocusNavigation& scope, int tabIndex, WebFocusType type)
 {
     // Search is inclusive of start
@@ skipping 903 matching lines @@
     return consumed;
 }
 
 DEFINE_TRACE(FocusController)
 {
     visitor->trace(m_page);
     visitor->trace(m_focusedFrame);
 }
 
 } // namespace blink