Merge pull request #201 from orbitjs/fix-array-proxy

Fix ReadOnlyArrayProxy for octane

Author: dgeb

addon/-private/system/read-only-array-proxy.js

@@ -1,4 +1,3 @@
-import { readOnly } from '@ember/object/computed';
 import { computed } from '@ember/object';
 import ArrayProxy from '@ember/array/proxy';
 
@@ -22,8 +21,6 @@ export default ArrayProxy.extend({
   unshiftObject: notSupported,
   unshiftObjects: notSupported,
 
-  length: readOnly('content.length'),
-
   init() {
     this._super();
     Object.defineProperty(this, Symbol.iterator, {