remove unused code

app/components/SimpleEditor/elements/track_change/TrackChangeControlCommand.js

@@ -11,7 +11,7 @@ class TrackChangeControlCommand extends Command {
   }
   execute (params, context) {
     const surface = context.surfaceManager.getSurface('body')
-    surface._owner.send('trackChangesUpdate')
+    surface.send('trackChangesUpdate')
     return true
   }
 }

app/components/SimpleEditor/elements/track_change/TrackChangePackage.js

@@ -19,7 +19,7 @@ export default {
     config.addTool('track-change-toggle-view', TrackChangeControlViewTool, {
       target: 'track-change-toggle-view'
     })
-    config.addCommand('track-change-enable', TrackChangeControlCommand, {target: 'document'})
+    config.addCommand('track-change-enable', TrackChangeControlCommand)
     config.addCommand('track-change-toggle-view', TrackChangeControlViewCommand)
     config.addCommand(TrackChange.type, TrackChangeCommand, { nodeType: TrackChange.type })
     config.addIcon('track-change', { 'fontawesome': 'fa-eye' })