Oilpan: Change Persistent members of Resource subclasses to Member.

Source/core/fetch/FontResource.cpp

Index: Source/core/fetch/FontResource.cpp
diff --git a/Source/core/fetch/FontResource.cpp b/Source/core/fetch/FontResource.cpp
index 7ad0f3b7bfebde0c03a83c5bd9c034f4f8b9e7a1..52ab3a1a1157bced05ad972bd5de4a3eb810c12d 100644
--- a/Source/core/fetch/FontResource.cpp
+++ b/Source/core/fetch/FontResource.cpp
@@ -87,6 +87,14 @@ FontResource::~FontResource()
 {
 }
 
+void FontResource::trace(Visitor* visitor)
+{
+#if ENABLE(SVG_FONTS)
+    visitor->trace(m_externalSVGDocument);
+#endif
+    Resource::trace(visitor);
+}
+
 void FontResource::load(ResourceFetcher*, const ResourceLoaderOptions& options)
 {
     // Don't load the file yet. Wait for an access before triggering the load.