Drop autorun assertion

This removes the autorun assertion in test mode. The original conditions that caused it to be added are no longer true, as we are on a version of backburner that uses microtask scheduling.

packages/@ember/runloop/index.js

@@ -1,4 +1,4 @@
-import { assert, deprecate, isTesting } from '@ember/debug';
+import { assert, deprecate } from '@ember/debug';
 import { onErrorTarget } from 'ember-error-handling';
 import { beginPropertyChanges, endPropertyChanges } from 'ember-metal';
 import Backburner from 'backburner';
@@ -325,11 +325,6 @@ export function end() {
   @public
 */
 export function schedule(queue /*, target, method */) {
-  assert(
-    `You have turned on testing mode, which disabled the run-loop's autorun. ` +
-      `You will need to wrap any code with asynchronous side-effects in a run`,
-    currentRunLoop || !isTesting()
-  );
   deprecate(`Scheduling into the '${queue}' run loop queue is deprecated.`, queue !== 'sync', {
     id: 'ember-metal.run.sync',
     until: '3.5.0',
@@ -398,11 +393,6 @@ export function later(/*target, method*/) {
   @public
 */
 export function once(...args) {
-  assert(
-    `You have turned on testing mode, which disabled the run-loop's autorun. ` +
-      `You will need to wrap any code with asynchronous side-effects in a run`,
-    currentRunLoop || !isTesting()
-  );
   args.unshift('actions');
   return backburner.scheduleOnce(...args);
 }
@@ -480,11 +470,6 @@ export function once(...args) {
   @public
 */
 export function scheduleOnce(queue /*, target, method*/) {
-  assert(
-    `You have turned on testing mode, which disabled the run-loop's autorun. ` +
-      `You will need to wrap any code with asynchronous side-effects in a run`,
-    currentRunLoop || !isTesting()
-  );
   deprecate(`Scheduling into the '${queue}' run loop queue is deprecated.`, queue !== 'sync', {
     id: 'ember-metal.run.sync',
     until: '3.5.0',

packages/@ember/runloop/tests/schedule_test.js

@@ -82,18 +82,5 @@ moduleFor(
 
       assert.deepEqual(order, ['sync', 'actions', 'sync', 'actions', 'destroy']);
     }
-
-    ['@test makes sure it does not trigger an autorun during testing']() {
-      expectAssertion(
-        () => schedule('actions', () => {}),
-        /wrap any code with asynchronous side-effects in a run/
-      );
-
-      // make sure not just the first violation is asserted.
-      expectAssertion(
-        () => schedule('actions', () => {}),
-        /wrap any code with asynchronous side-effects in a run/
-      );
-    }
   }
 );