Oilpan: RenderMenuList should call PopupMenu::disconnectClient in destroy().

Source/core/rendering/RenderMenuList.cpp

Index: Source/core/rendering/RenderMenuList.cpp
diff --git a/Source/core/rendering/RenderMenuList.cpp b/Source/core/rendering/RenderMenuList.cpp
index 08e8db8846753b328a0c401628cc8219a152edf5..1af6a78f40742714009caebd2035596e62b4cecd 100644
--- a/Source/core/rendering/RenderMenuList.cpp
+++ b/Source/core/rendering/RenderMenuList.cpp
@@ -65,9 +65,15 @@ RenderMenuList::RenderMenuList(Element* element)
 
 RenderMenuList::~RenderMenuList()
 {
+    ASSERT(!m_popup);
+}
+
+void RenderMenuList::destroy()
+{
     if (m_popup)
         m_popup->disconnectClient();
     m_popup = nullptr;
+    RenderFlexibleBox::destroy();
 }
 
 void RenderMenuList::trace(Visitor* visitor)