Listen for ‘blur’ on mini editor of select list rather than ‘focusout’

The focusout handler on the mini editor’s hidden input wasn’t being
triggered, but we can listen for blur directly on the editor now that
the shadow DOM abstracts the focus.

src/select-list-view.coffee

@@ -57,7 +57,7 @@ class SelectListView extends View
   initialize: ->
     @filterEditorView.getEditor().getBuffer().onDidChange =>
       @schedulePopulateList()
-    @filterEditorView.hiddenInput.on 'focusout', =>
+    @filterEditorView.on 'blur', =>
       @cancel() unless @cancelling
 
     # This prevents the focusout event from firing on the filter editor view