d3dx9: Don't return a pointer to the implementation in ID3DXEffectImpl_QueryInterface().

dlls/d3dx9_36/effect.c

@@ -2778,15 +2778,13 @@ static inline struct ID3DXEffectImpl *impl_from_ID3DXEffect(ID3DXEffect *iface)
 /*** IUnknown methods ***/
 static HRESULT WINAPI ID3DXEffectImpl_QueryInterface(ID3DXEffect *iface, REFIID riid, void **object)
 {
-    struct ID3DXEffectImpl *This = impl_from_ID3DXEffect(iface);
-
-    TRACE("(%p)->(%s, %p)\n", This, debugstr_guid(riid), object);
+    TRACE("(%p)->(%s, %p)\n", iface, debugstr_guid(riid), object);
 
     if (IsEqualGUID(riid, &IID_IUnknown) ||
         IsEqualGUID(riid, &IID_ID3DXEffect))
     {
-        This->ID3DXEffect_iface.lpVtbl->AddRef(iface);
-        *object = This;
+        iface->lpVtbl->AddRef(iface);
+        *object = iface;
         return S_OK;
     }