Oilpan: move SVG property hierarchy to the heap.

Source/core/svg/SVGMaskElement.cpp

Index: Source/core/svg/SVGMaskElement.cpp
diff --git a/Source/core/svg/SVGMaskElement.cpp b/Source/core/svg/SVGMaskElement.cpp
index b3391238dd6417246647b14e441c60dd7c567584..47462002fa618be51db166c04fbb96b538e33287 100644
--- a/Source/core/svg/SVGMaskElement.cpp
+++ b/Source/core/svg/SVGMaskElement.cpp
@@ -55,6 +55,18 @@ inline SVGMaskElement::SVGMaskElement(Document& document)
     addToPropertyMap(m_maskContentUnits);
 }
 
+void SVGMaskElement::trace(Visitor* visitor)
+{
+    visitor->trace(m_x);
+    visitor->trace(m_y);
+    visitor->trace(m_width);
+    visitor->trace(m_height);
+    visitor->trace(m_maskUnits);
+    visitor->trace(m_maskContentUnits);
+    SVGElement::trace(visitor);
+    SVGTests::trace(visitor);
+}
+
 DEFINE_NODE_FACTORY(SVGMaskElement)
 
 bool SVGMaskElement::isSupportedAttribute(const QualifiedName& attrName)