fix: 删除不必要渲染

Author: AliceLanniste

packages/core/plugin/GroupPlugin.ts

@@ -43,7 +43,6 @@ class GroupPlugin implements IPluginTempl {
         this.canvas.remove(object);
       });
       this.canvas.add(newgroup);
-      this.canvas.discardActiveObject().renderAll();
     });
   }