Properly retain non-node event listeners.

Source/WebCore/bindings/dart/DartDOMWrapper.h

Index: Source/WebCore/bindings/dart/DartDOMWrapper.h
diff --git a/Source/WebCore/bindings/dart/DartDOMWrapper.h b/Source/WebCore/bindings/dart/DartDOMWrapper.h
index 763b68ca6106c4df881705d83ee909806e02f066..78168d59724560fde840889d14573965f3e15634 100644
--- a/Source/WebCore/bindings/dart/DartDOMWrapper.h
+++ b/Source/WebCore/bindings/dart/DartDOMWrapper.h
@@ -83,6 +83,7 @@ public:
         Dart_Handle persistentWrapperHandle = DartUtilities::createPrologueWeakPersistentHandle(wrapper, domObject, &wrapperWeakCallback<BindingsClass>);
         Traits::MapTraits::domMap(domData)->set(domObject, persistentWrapperHandle);
         Traits::ActiveTraits::setWrapper(domData, domObject, persistentWrapperHandle);
+        Traits::EventTargetTraits::setWrapper(domData, domObject, persistentWrapperHandle);
         domObject->ref();
         return wrapper;
     }
@@ -188,6 +189,7 @@ private:
         ASSERT(DartDOMWrapperTraits<BindingsClass>::MapTraits::domMap(domData)->contains(domObject));
         Traits::MapTraits::domMap(domData)->remove(domObject);
         Traits::ActiveTraits::removeWrapper(domData, domObject);
+        Traits::EventTargetTraits::removeWrapper(domData, domObject);
         domObject->deref();
     }
 };
@@ -227,10 +229,35 @@ struct DartDOMWrapperActiveTraits<BindingsClass, true> {
     }
 };
 
+template<class BindingsClass, bool isEventTarget>
+struct DartDOMWrapperEventTargetTraits {};
+
+template<class BindingsClass>
+struct DartDOMWrapperEventTargetTraits<BindingsClass, false> {
+    static void setWrapper(DartDOMData*, typename BindingsClass::NativeType*, Dart_Handle) {}
+    static void removeWrapper(DartDOMData*, typename BindingsClass::NativeType*) {}
+};
+
+template<class BindingsClass>
+struct DartDOMWrapperEventTargetTraits<BindingsClass, true> {
+    static void setWrapper(DartDOMData* domData, typename BindingsClass::NativeType* domObject, Dart_Handle wrapper)
+    {
+        domData->eventTargetMap()->set(domObject, wrapper);
+    }
+
+    static void removeWrapper(DartDOMData* domData, typename BindingsClass::NativeType* domObject)
+    {
+        domData->eventTargetMap()->remove(domObject);
+    }
+};
+
 template<class BindingsClass>
 struct DartDOMWrapperTraits {
     typedef DartDOMWrapperMapTraits<BindingsClass::isNode> MapTraits;
     typedef DartDOMWrapperActiveTraits<BindingsClass, BindingsClass::isActive> ActiveTraits;
+    // Putting all the nodes into additional map is expensive. Instead, we have
+    // special treatment of node event listeners in GC prologue.
+    typedef DartDOMWrapperEventTargetTraits<BindingsClass, BindingsClass::isEventTarget && !BindingsClass::isNode> EventTargetTraits;
 };
 
 struct DartMessagePort;
@@ -242,6 +269,7 @@ struct DartDOMWrapperTraits<DartMessagePort> {
     };
     typedef MessagePortMapTraits MapTraits;
     typedef DartDOMWrapperActiveTraits<DartMessagePort, false> ActiveTraits;
+    typedef DartDOMWrapperEventTargetTraits<DartMessagePort, true> EventTargetTraits;
 };
 
 }