Trigger editor:will-be-removed from SpacePen shim, not component

By the time the component is getting unmounted, we have already called
remove hooks on the SpacePen shim so subscriptions to the event have
been removed.

src/text-editor-component.coffee

@@ -199,7 +199,6 @@ TextEditorComponent = React.createClass
   componentWillUnmount: ->
     {editor, hostElement} = @props
 
-    hostElement.__spacePenView.trigger 'editor:will-be-removed', [hostElement.__spacePenView]
     @unsubscribe()
     @scopedConfigSubscriptions.dispose()
     window.removeEventListener 'resize', @requestHeightAndWidthMeasurement

src/text-editor-view.coffee

@@ -138,6 +138,7 @@ class TextEditorView extends View
 
   beforeRemove: ->
     @trigger 'editor:detached', [this]
+    @trigger 'editor:will-be-removed', [this]
     @attached = false
 
   remove: (selector, keepData) ->