IDL: Generate trace() method in union container types when required

Source/bindings/tests/results/core/UnionTypesCore.cpp

Index: Source/bindings/tests/results/core/UnionTypesCore.cpp
diff --git a/Source/bindings/tests/results/core/UnionTypesCore.cpp b/Source/bindings/tests/results/core/UnionTypesCore.cpp
index 37ca49de8fc8ccd2a4ee5d64f5b448aca97a6b1d..b71387c8f08fe27c7030e0c6d7441060f0a74dbc 100644
--- a/Source/bindings/tests/results/core/UnionTypesCore.cpp
+++ b/Source/bindings/tests/results/core/UnionTypesCore.cpp
@@ -143,6 +143,12 @@ void NodeOrNodeList::setNodeList(PassRefPtrWillBeRawPtr<NodeList> value)
     m_type = SpecificTypeNodeList;
 }
 
+void NodeOrNodeList::trace(Visitor* visitor)
+{
+    visitor->trace(m_node);
+    visitor->trace(m_nodeList);
+}
+
 void V8NodeOrNodeList::toImpl(v8::Isolate* isolate, v8::Handle<v8::Value> v8Value, NodeOrNodeList& impl, ExceptionState& exceptionState)
 {
     if (v8Value.IsEmpty() || isUndefinedOrNull(v8Value))
@@ -275,6 +281,11 @@ void TestInterfaceGarbageCollectedOrString::setString(String value)
     m_type = SpecificTypeString;
 }
 
+void TestInterfaceGarbageCollectedOrString::trace(Visitor* visitor)
+{
+    visitor->trace(m_testInterfaceGarbageCollected);
+}
+
 void V8TestInterfaceGarbageCollectedOrString::toImpl(v8::Isolate* isolate, v8::Handle<v8::Value> v8Value, TestInterfaceGarbageCollectedOrString& impl, ExceptionState& exceptionState)
 {
     if (v8Value.IsEmpty() || isUndefinedOrNull(v8Value))
@@ -479,6 +490,11 @@ void TestInterfaceWillBeGarbageCollectedOrTestDictionary::setTestDictionary(Test
     m_type = SpecificTypeTestDictionary;
 }
 
+void TestInterfaceWillBeGarbageCollectedOrTestDictionary::trace(Visitor* visitor)
+{
+    visitor->trace(m_testInterfaceWillBeGarbageCollected);
+}
+
 void V8TestInterfaceWillBeGarbageCollectedOrTestDictionary::toImpl(v8::Isolate* isolate, v8::Handle<v8::Value> v8Value, TestInterfaceWillBeGarbageCollectedOrTestDictionary& impl, ExceptionState& exceptionState)
 {
     if (v8Value.IsEmpty() || isUndefinedOrNull(v8Value))