Have DOMImplementation::document() return reference.

Source/bindings/tests/results/V8TestInterfacePython3.cpp

Index: Source/bindings/tests/results/V8TestInterfacePython3.cpp
diff --git a/Source/bindings/tests/results/V8TestInterfacePython3.cpp b/Source/bindings/tests/results/V8TestInterfacePython3.cpp
index 98d25492c7f9839dde760dab8975bdf41fc5bcee..738f7f0c9446838b65987f8340eb4afed0049aa6 100644
--- a/Source/bindings/tests/results/V8TestInterfacePython3.cpp
+++ b/Source/bindings/tests/results/V8TestInterfacePython3.cpp
@@ -36,9 +36,11 @@
 #include "RuntimeEnabledFeatures.h"
 #include "bindings/v8/ExceptionState.h"
 #include "bindings/v8/V8DOMConfiguration.h"
+#include "bindings/v8/V8GCController.h"
 #include "bindings/v8/V8ObjectConstructor.h"
 #include "core/dom/ContextFeatures.h"
 #include "core/dom/Document.h"
+#include "core/dom/Element.h"
 #include "platform/TraceEvent.h"
 #include "wtf/GetPtr.h"
 #include "wtf/RefPtr.h"
@@ -73,6 +75,13 @@ template <typename T> void V8_USE(T) { }
 
 } // namespace TestInterfacePython3V8Internal
 
+void V8TestInterfacePython3::visitDOMWrapper(void* object, const v8::Persistent<v8::Object>& wrapper, v8::Isolate* isolate)
+{
+    TestInterfacePython3* impl = fromInternalPointer(object);
+    Node* root = V8GCController::opaqueRootForGC(&impl->document(), isolate);
+    isolate->SetReferenceFromGroup(v8::UniqueId(reinterpret_cast<intptr_t>(root)), wrapper);
+}
+
 static void configureV8TestInterfacePython3Template(v8::Handle<v8::FunctionTemplate> functionTemplate, v8::Isolate* isolate, WrapperWorldType currentWorldType)
 {
     functionTemplate->ReadOnlyPrototype();