Dispose emitter after emitting did-destroy

src/editor.coffee

@@ -172,6 +172,7 @@ class Editor extends Model
     @displayBuffer.destroy()
     @languageMode.destroy()
     @emitter.emit 'did-destroy'
+    @emitter.dispose()
 
   ###
   Section: Event Subscription

src/pane.coffee

@@ -518,6 +518,7 @@ class Pane extends Model
   destroyed: ->
     @container.activateNextPane() if @isActive()
     @emitter.emit 'did-destroy'
+    @emitter.dispose()
     item.destroy?() for item in @items.slice()
 
   ###