Remove arity check from initializer

packages/ember-application/lib/system/engine.js

@@ -12,7 +12,7 @@ import {
   privatize as P
 } from 'container';
 import DAG from 'dag-map';
-import { assert, deprecate } from 'ember-debug';
+import { assert } from 'ember-debug';
 import { get, set } from 'ember-metal';
 import DefaultResolver from './resolver';
 import EngineInstance from './engine-instance';
@@ -124,18 +124,7 @@ const Engine = Namespace.extend(RegistryProxyMixin, {
   runInitializers() {
     this._runInitializer('initializers', (name, initializer) => {
       assert(`No application initializer named '${name}'`, !!initializer);
-      if (initializer.initialize.length === 2) {
-        deprecate(`The \`initialize\` method for Application initializer '${name}' should take only one argument - \`App\`, an instance of an \`Application\`.`,
-          false, {
-            id: 'ember-application.app-initializer-initialize-arguments',
-            until: '3.0.0',
-            url: 'https://emberjs.com/deprecations/v2.x/#toc_initializer-arity'
-          });
-
-        initializer.initialize(this.__registry__, this);
-      } else {
-        initializer.initialize(this);
-      }
+      initializer.initialize(this);
     });
   },
 
@@ -474,7 +463,7 @@ function resolverFor(namespace) {
 }
 
 function buildInitializerMethod(bucketName, humanName) {
-  return function(initializer) {
+  return function (initializer) {
     // If this is the first initializer being added to a subclass, we are going to reopen the class
     // to make sure we have a new `initializers` object, which extends from the parent class' using
     // prototypal inheritance. Without this, attempting to add initializers to the subclass would

packages/ember-application/tests/system/initializers_test.js

@@ -18,7 +18,7 @@ moduleFor('Ember.Application initializers', class extends AutobootApplicationTes
     });
   }
 
-  createSecondApplication(options, MyApplication=Application) {
+  createSecondApplication(options, MyApplication = Application) {
     let myOptions = assign(this.applicationOptions, {
       rootElement: '#two'
     }, options);
@@ -42,7 +42,7 @@ moduleFor('Ember.Application initializers', class extends AutobootApplicationTes
     });
 
     expectAssertion(() => {
-      MyApplication.initializer({ initialize() {} });
+      MyApplication.initializer({ initialize() { } });
     });
   }
 
@@ -329,20 +329,20 @@ moduleFor('Ember.Application initializers', class extends AutobootApplicationTes
 
     FirstApp.initializer({
       name: 'abc',
-      initialize() {}
+      initialize() { }
     });
 
     expectAssertion(() => {
       FirstApp.initializer({
         name: 'abc',
-        initialize() {}
+        initialize() { }
       });
     });
 
     let SecondApp = Application.extend();
     SecondApp.instanceInitializer({
       name: 'abc',
-      initialize() {}
+      initialize() { }
     });
 
     assert.ok(true, 'Two apps can have initializers named the same.');
@@ -362,20 +362,4 @@ moduleFor('Ember.Application initializers', class extends AutobootApplicationTes
 
     this.runTask(() => this.createApplication({}, MyApplication));
   }
-
-  [`@test initializers throw a deprecation warning when receiving a second argument`](assert) {
-    assert.expect(1);
-
-    let MyApplication = Application.extend();
-
-    MyApplication.initializer({
-      name: 'deprecated',
-      initialize(registry, application) { // eslint-disable-line no-unused-vars
-      }
-    });
-
-    expectDeprecation(() => {
-      this.runTask(() => this.createApplication({}, MyApplication));
-    }, /The `initialize` method for Application initializer 'deprecated' should take only one argument - `App`, an instance of an `Application`./);
-  }
 });