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 642 matching lines @@
 {
     if (index == m_activeSelectionEndIndex)
         return;
     m_activeSelectionEndIndex = index;
     setNeedsStyleRecalc(SubtreeStyleChange, StyleChangeReasonForTracing::create(StyleChangeReason::Control));
 }
 
 void HTMLSelectElement::updateListBoxSelection(bool deselectOtherOptions, bool scroll)
 {
     ASSERT(renderer() && (renderer()->isListBox() || m_multiple));
-    ASSERT(!listItems().size() || m_activeSelectionAnchorIndex >= 0);
 
-    unsigned start = std::min(m_activeSelectionAnchorIndex, m_activeSelectionEndIndex);
-    unsigned end = std::max(m_activeSelectionAnchorIndex, m_activeSelectionEndIndex);
+    int start = std::min(m_activeSelectionAnchorIndex, m_activeSelectionEndIndex);
+    int end = std::max(m_activeSelectionAnchorIndex, m_activeSelectionEndIndex);
 
     const WillBeHeapVector<RawPtrWillBeMember<HTMLElement>>& items = listItems();
-    for (unsigned i = 0; i < items.size(); ++i) {
+    for (int i = 0; i < static_cast<int>(items.size()); ++i) {
         HTMLElement* element = items[i];
         if (!isHTMLOptionElement(*element) || toHTMLOptionElement(element)->isDisabledFormControl() || !toHTMLOptionElement(element)->renderer())
             continue;
 
         if (i >= start && i <= end)
             toHTMLOptionElement(element)->setSelectedState(m_activeSelectionState);
-        else if (deselectOtherOptions || i >= m_cachedStateForActiveSelection.size())
+        else if (deselectOtherOptions || i >= static_cast<int>(m_cachedStateForActiveSelection.size()))
             toHTMLOptionElement(element)->setSelectedState(false);
         else
             toHTMLOptionElement(element)->setSelectedState(m_cachedStateForActiveSelection[i]);
     }
 
     setNeedsValidityCheck();
     if (scroll)
         scrollToSelection();
     notifyFormStateChanged();
 }
@@ skipping 1087 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