Oilpan: Prepare to move RenderObject and RenderObjectChildList to Oilpan heap.

Source/core/rendering/RenderMedia.cpp

Index: Source/core/rendering/RenderMedia.cpp
diff --git a/Source/core/rendering/RenderMedia.cpp b/Source/core/rendering/RenderMedia.cpp
index 623041c6afa374c508f65854decf321465b5ccd4..08994661a9b5a82362dc2eb6190a23eae6250b35 100644
--- a/Source/core/rendering/RenderMedia.cpp
+++ b/Source/core/rendering/RenderMedia.cpp
@@ -42,6 +42,12 @@ RenderMedia::~RenderMedia()
 {
 }
 
+void RenderMedia::trace(Visitor* visitor)
+{
+    visitor->trace(m_children);
+    RenderImage::trace(visitor);
+}
+
 HTMLMediaElement* RenderMedia::mediaElement() const
 {
     return toHTMLMediaElement(node());