DEV: Remove EventTarget. Future versions of Ember don't export this.

It was removed altogether from ApplicationRoute, which only triggered
an `activate` event which never seems to be used.

We can replace it with Evented which is still present.

app/assets/javascripts/discourse-loader.js

@@ -108,7 +108,6 @@ var define, requirejs;
       },
       rsvp: {
         default: Ember.RSVP,
-        EventTarget: Ember.RSVP.EventTarget,
         Promise: Ember.RSVP.Promise,
         hash: Ember.RSVP.hash,
         all: Ember.RSVP.all

app/assets/javascripts/discourse/lib/eyeline.js

@@ -1,5 +1,5 @@
 import ENV from "discourse-common/config/environment";
-import { EventTarget } from "rsvp";
+import AppEvents from "discourse/services/app-events";
 
 let _skipUpdate;
 let _rootElement;
@@ -19,6 +19,15 @@ configureEyeline();
 //  Track visible elements on the screen.
 const Eyeline = function Eyeline(selector) {
   this.selector = selector;
+  this.appEvents = AppEvents.create();
+};
+
+Eyeline.prototype.on = function(name, cb) {
+  this.appEvents.on(name, cb);
+};
+
+Eyeline.prototype.off = function(name, cb) {
+  this.appEvents.off(name, cb);
 };
 
 Eyeline.prototype.update = function() {
@@ -44,6 +53,7 @@ Eyeline.prototype.update = function() {
       bottomOffset.top <= docViewBottom && bottomOffset.top >= docViewTop;
   }
 
+  let { appEvents } = this;
   return $elements.each((i, elem) => {
     const $elem = $(elem),
       elemTop = _rootElement ? $elem.position().top : $elem.offset().top,
@@ -68,17 +78,17 @@ Eyeline.prototype.update = function() {
 
     // If you hit the bottom we mark all the elements as seen. Otherwise, just the first one
     if (!atBottom) {
-      this.trigger("saw", { detail: $elem });
+      appEvents.trigger("saw", { detail: $elem });
       if (i === 0) {
-        this.trigger("sawTop", { detail: $elem });
+        appEvents.trigger("sawTop", { detail: $elem });
       }
       return false;
     }
     if (i === 0) {
-      this.trigger("sawTop", { detail: $elem });
+      appEvents.trigger("sawTop", { detail: $elem });
     }
     if (i === $elements.length - 1) {
-      return this.trigger("sawBottom", { detail: $elem });
+      return appEvents.trigger("sawBottom", { detail: $elem });
     }
   });
 };
@@ -89,9 +99,9 @@ Eyeline.prototype.flushRest = function() {
     return;
   }
 
-  $(this.selector).each((i, elem) => this.trigger("saw", { detail: $(elem) }));
+  $(this.selector).each((i, elem) =>
+    this.appEvents.trigger("saw", { detail: $(elem) })
+  );
 };
 
-EventTarget.mixin(Eyeline.prototype);
-
 export default Eyeline;

app/assets/javascripts/discourse/routes/application.js

@@ -1,4 +1,4 @@
-import { next, once } from "@ember/runloop";
+import { once } from "@ember/runloop";
 import DiscourseRoute from "discourse/routes/discourse";
 import { ajax } from "discourse/lib/ajax";
 import { setting } from "discourse/lib/computed";
@@ -11,7 +11,6 @@ import { findAll } from "discourse/models/login-method";
 import { getOwner } from "discourse-common/lib/get-owner";
 import { userPath } from "discourse/lib/url";
 import Composer from "discourse/models/composer";
-import { EventTarget } from "rsvp";
 
 function unlessReadOnly(method, message) {
   return function() {
@@ -236,14 +235,6 @@ const ApplicationRoute = DiscourseRoute.extend(OpenComposer, {
     }
   },
 
-  activate() {
-    this._super(...arguments);
-    next(function() {
-      // Support for callbacks once the application has activated
-      ApplicationRoute.trigger("activate");
-    });
-  },
-
   renderTemplate() {
     this.render("application");
     this.render("user-card", { into: "application", outlet: "user-card" });
@@ -298,5 +289,4 @@ const ApplicationRoute = DiscourseRoute.extend(OpenComposer, {
   }
 });
 
-EventTarget.mixin(ApplicationRoute);
 export default ApplicationRoute;

app/assets/javascripts/discourse/routes/topic.js

@@ -4,13 +4,13 @@ import { cancel, later, schedule } from "@ember/runloop";
 import DiscourseRoute from "discourse/routes/discourse";
 import DiscourseURL from "discourse/lib/url";
 import { ID_CONSTRAINT } from "discourse/models/topic";
-import { EventTarget } from "rsvp";
+import Evented from "@ember/object/evented";
 
 const SCROLL_DELAY = 500;
 
 import showModal from "discourse/lib/show-modal";
 
-const TopicRoute = DiscourseRoute.extend({
+const TopicRoute = DiscourseRoute.extend(Evented, {
   init() {
     this._super(...arguments);
 
@@ -332,5 +332,4 @@ const TopicRoute = DiscourseRoute.extend({
   }
 });
 
-EventTarget.mixin(TopicRoute);
 export default TopicRoute;

app/assets/javascripts/discourse/services/app-events.js

@@ -3,7 +3,10 @@ import Evented from "@ember/object/evented";
 import Service from "@ember/service";
 
 export default Service.extend(Evented, {
-  _events: {},
+  init() {
+    this._super(...arguments);
+    this._events = {};
+  },
 
   on() {
     if (arguments.length === 2) {