PERF: stop destroying drafts on client when posting replies

The server already ensures it advances draft keys when a post is created
this means this code that used to delete drafts is simply introducing
composer delays with no benefit.

app/assets/javascripts/discourse/controllers/composer.js.es6

@@ -687,16 +687,6 @@ export default Controller.extend({
           });
         }
 
-        // If user "created a new topic/post" or "replied as a new topic" successfully, remove the draft.
-        let destroyDraftPromise;
-
-        if (result.responseJson.action === "create_post") {
-          destroyDraftPromise = this.destroyDraft();
-        } else {
-          destroyDraftPromise = Ember.RSVP.Promise.resolve();
-        }
-
-        return destroyDraftPromise.then(() => {
         if (this.get("model.editingPost")) {
           this.appEvents.trigger("post-stream:refresh", {
             id: parseInt(result.responseJson.id)
@@ -709,10 +699,7 @@ export default Controller.extend({
         }
 
         if (result.responseJson.action === "create_post") {
-            this.appEvents.trigger(
+          this.appEvents.trigger("post:highlight", result.payload.post_number);
-              "post:highlight",
-              result.payload.post_number
-            );
         }
         this.close();
 
@@ -727,7 +714,6 @@ export default Controller.extend({
         if (post && !staged) {
           DiscourseURL.routeTo(post.url);
         }
-        });
       })
       .catch(error => {
         composer.set("disableDrafts", false);