Fix change tracking so that it doesn't prompt you to save when closing right after you clicked save

MaterialGraphProject/Assets/GraphFramework/SerializableGraph/Editor/Implementation/SerializableGraphObject.cs

         public bool isDirty
         {
             get { return m_IsDirty; }
+            set { m_IsDirty = value; }
         }
 
         public void RegisterCompleteObjectUndo(string name)

MaterialGraphProject/Assets/UnityShaderEditor/Editor/Drawing/MaterialGraphEditWindow.cs

                 if (m_GraphObject.graph.GetType() == typeof(MasterRemapGraph))
                     UpdateAbstractSubgraphOnDisk<MasterRemapGraph>(path);
 
+                graphObject.isDirty = false;
                 var windows = Resources.FindObjectsOfTypeAll<MaterialGraphEditWindow>();
                 foreach (var materialGraphEditWindow in windows)
                 {