Fix listbox selections with only disabled options.

Source/core/html/HTMLSelectElement.cpp

 /*
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2009, 2010, 2011 Apple Inc. All rights reserved.
  *           (C) 2006 Alexey Proskuryakov (ap@nypop.com)
  * Copyright (C) 2010 Google Inc. All rights reserved.
  * Copyright (C) 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  *
@@ skipping 596 matching lines @@
         return;
 
     // Save the selection so it can be compared to the new selectAll selection
     // when dispatching change events.
     saveLastSelection();
 
     m_activeSelectionState = true;
     setActiveSelectionAnchorIndex(nextSelectableListIndex(-1));
     setActiveSelectionEndIndex(previousSelectableListIndex(-1));
 
+    if (m_activeSelectionAnchorIndex < 0)

[keishi, 2014/12/02 02:40:13]

I think updateListBoxSelection should just be able to handle the no active
selection case.
We can just remove the ASSERT and changed the unsigned variables to ints.

+        return;
+
     updateListBoxSelection(false, false);
     listBoxOnChange();
     setNeedsValidityCheck();
 }
 
 void HTMLSelectElement::saveLastSelection()
 {
     if (usesMenuList()) {
         m_lastOnChangeIndex = selectedIndex();
         return;
@@ skipping 1147 matching lines @@
     int focusedIndex = activeSelectionEndListIndex();
     if (focusedIndex < 0)
         focusedIndex = firstSelectableListIndex();
     if (focusedIndex < 0)
         return nullptr;
     HTMLElement* focused = listItems()[focusedIndex];
     return isHTMLOptionElement(focused) ? toHTMLOptionElement(focused) : nullptr;
 }
 
 } // namespace