[oilpan] Completely move HTMLFormControlElement's hierarchy to the managed heap

Source/core/rendering/RenderListBox.cpp

Index: Source/core/rendering/RenderListBox.cpp
diff --git a/Source/core/rendering/RenderListBox.cpp b/Source/core/rendering/RenderListBox.cpp
index 15eed0c8c1e4d2353c3367eff1dc4268c8086ca4..98a0d202ef5600a22513c36d2be205f285ef9b76 100644
--- a/Source/core/rendering/RenderListBox.cpp
+++ b/Source/core/rendering/RenderListBox.cpp
@@ -105,7 +105,7 @@ RenderListBox::~RenderListBox()
         frameView->removeScrollableArea(this);
 }
 
-inline HTMLSelectElement* RenderListBox::selectElement() const
+inline Result<HTMLSelectElement> RenderListBox::selectElement() const
 {
     return toHTMLSelectElement(node());
 }
@@ -194,7 +194,7 @@ void RenderListBox::layout()
 
 void RenderListBox::scrollToRevealSelection()
 {    
-    HTMLSelectElement* select = selectElement();
+    Handle<HTMLSelectElement> select = selectElement();
 
     m_scrollToRevealSelectionAfterLayout = false;
 
@@ -332,7 +332,7 @@ void RenderListBox::addFocusRingRects(Vector<IntRect>& rects, const LayoutPoint&
     if (!isSpatialNavigationEnabled(frame()))
         return RenderBlock::addFocusRingRects(rects, additionalOffset, paintContainer);
 
-    HTMLSelectElement* select = selectElement();
+    Handle<HTMLSelectElement> select = selectElement();
 
     // Focus the last selected item.
     int selectedItem = select->activeSelectionEndListIndex();
@@ -389,7 +389,7 @@ void RenderListBox::paintItemForeground(PaintInfo& paintInfo, const LayoutPoint&
 {
     FontCachePurgePreventer fontCachePurgePreventer;
 
-    HTMLSelectElement* select = selectElement();
+    Handle<HTMLSelectElement> select = selectElement();
 
     const Vector<HTMLElement*>& listItems = select->listItems();
     HTMLElement* element = listItems[listIndex];
@@ -534,7 +534,7 @@ void RenderListBox::panScroll(const IntPoint& panStartMousePosition)
         return;
 
     m_inAutoscroll = true;
-    HTMLSelectElement* select = selectElement();
+    Handle<HTMLSelectElement> select = selectElement();
     select->updateListBoxSelection(!select->multiple());
     m_inAutoscroll = false;
 }
@@ -563,7 +563,7 @@ void RenderListBox::autoscroll(const IntPoint&)
 
     int endIndex = scrollToward(pos);
     if (endIndex >= 0) {
-        HTMLSelectElement* select = selectElement();
+        Handle<HTMLSelectElement> select = selectElement();
         m_inAutoscroll = true;
 
         if (!select->multiple())
@@ -613,7 +613,7 @@ bool RenderListBox::logicalScroll(ScrollLogicalDirection direction, ScrollGranul
 
 void RenderListBox::valueChanged(unsigned listIndex)
 {
-    HTMLSelectElement* element = selectElement();
+    Handle<HTMLSelectElement> element = selectElement();
     element->setSelectedIndex(element->listToOptionIndex(listIndex));
     element->dispatchFormControlChangeEvent();
 }