Implement select listbox using shadow DOM

Source/core/accessibility/AXListBoxOption.cpp

Index: Source/core/accessibility/AXListBoxOption.cpp
diff --git a/Source/core/accessibility/AXListBoxOption.cpp b/Source/core/accessibility/AXListBoxOption.cpp
index 8e24712572eae69f9692a6b64fb0cfe520f04468..d19901878ff8b3b849e17c2a36f53b6842f772c3 100644
--- a/Source/core/accessibility/AXListBoxOption.cpp
+++ b/Source/core/accessibility/AXListBoxOption.cpp
@@ -88,28 +88,6 @@ bool AXListBoxOption::isSelectedOptionActive() const
     return listBoxParentNode->activeSelectionEndListIndex() == listBoxOptionIndex();
 }
 
-LayoutRect AXListBoxOption::elementRect() const
-{
-    LayoutRect rect;
-    if (!m_optionElement)
-        return rect;
-
-    HTMLSelectElement* listBoxParentNode = listBoxOptionParentNode();
-    if (!listBoxParentNode)
-        return rect;
-
-    RenderObject* listBoxRenderer = listBoxParentNode->renderer();
-    if (!listBoxRenderer)
-        return rect;
-
-    LayoutRect parentRect = listBoxRenderer->document().axObjectCache()->getOrCreate(listBoxRenderer)->elementRect();
-    int index = listBoxOptionIndex();
-    if (index != -1)
-        rect = toRenderListBox(listBoxRenderer)->itemBoundingBoxRect(parentRect.location(), index);
-
-    return rect;
-}
-
 bool AXListBoxOption::computeAccessibilityIsIgnored() const
 {
     if (!m_optionElement)