Oilpan: move SVG property hierarchy to the heap.

Source/core/svg/SVGGradientElement.cpp

Index: Source/core/svg/SVGGradientElement.cpp
diff --git a/Source/core/svg/SVGGradientElement.cpp b/Source/core/svg/SVGGradientElement.cpp
index 18e7813cba76c0c8ad8db48fdf0a5cdcccb702b8..c4431ebbaca6a18b967655e2e365a7c03915eeaa 100644
--- a/Source/core/svg/SVGGradientElement.cpp
+++ b/Source/core/svg/SVGGradientElement.cpp
@@ -57,6 +57,15 @@ SVGGradientElement::SVGGradientElement(const QualifiedName& tagName, Document& d
     addToPropertyMap(m_gradientUnits);
 }
 
+void SVGGradientElement::trace(Visitor* visitor)
+{
+    visitor->trace(m_gradientTransform);
+    visitor->trace(m_spreadMethod);
+    visitor->trace(m_gradientUnits);
+    SVGElement::trace(visitor);
+    SVGURIReference::trace(visitor);
+}
+
 bool SVGGradientElement::isSupportedAttribute(const QualifiedName& attrName)
 {
     DEFINE_STATIC_LOCAL(HashSet<QualifiedName>, supportedAttributes, ());