Fix config parameter default building in tracks.js; ideally this turn…

…s into classes when the multiple inheritance is fixed/refactored, and we can use simple static getter/setter methods.

client/galaxy/scripts/viz/trackster/tracks.js

@@ -251,7 +251,10 @@ var Drawable = function(view, container, obj_dict) {
     this.action_icons = {};
 
     // -- Set up drawable configuration. --
-    this.config = config_mod.ConfigSettingCollection.from_models_and_saved_values(this.config_params, obj_dict.prefs);
+    this.config = config_mod.ConfigSettingCollection.from_models_and_saved_values(
+        this.build_config_params(),
+        obj_dict.prefs
+    );
 
     // If there's no saved name, use object name.
     if (!this.config.get_value("name")) {
@@ -345,6 +348,10 @@ extend(Drawable.prototype, {
         }
     ],
 
+    build_config_params: function() {
+        return this.config_params;
+    },
+
     config_onchange: function() {},
 
     init: function() {},