Revert "[BUGFIX] Fix an issue with concatenatedProperties."

This reverts commit 0158de0.

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

@@ -682,7 +682,7 @@ Ember.Application.reopenClass({
   initializer: function(initializer) {
     var initializers = get(this, 'initializers');
 
-    Ember.assert("The initializer '" + initializer.name + "' has already been registered", !Ember.A(initializers).findBy('name', initializers.name));
+    Ember.assert("The initializer '" + initializer.name + "' has already been registered", !initializers.findBy('name', initializers.name));
     Ember.assert("An initializer cannot be registered with both a before and an after", !(initializer.before && initializer.after));
     Ember.assert("An initializer cannot be registered without an initialize function", Ember.canInvoke(initializer, 'initialize'));
 

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

@@ -130,37 +130,3 @@ test("initializers can have multiple dependencies", function () {
   });
 });
 
-test("initializers set on Application subclasses should not be shared between apps", function(){
-  var firstInitializerRunCount = 0, secondInitializerRunCount = 0;
-  var FirstApp = Ember.Application.extend();
-  FirstApp.initializer({
-    name: 'first',
-    initialize: function(container) {
-      firstInitializerRunCount++;
-    }
-  });
-  var SecondApp = Ember.Application.extend();
-  SecondApp.initializer({
-    name: 'second',
-    initialize: function(container) {
-      secondInitializerRunCount++;
-    }
-  });
-  Ember.$('#qunit-fixture').html('<div id="first"></div><div id="second"></div>');
-  Ember.run(function() {
-    var firstApp = FirstApp.create({
-      router: false,
-      rootElement: '#qunit-fixture #first'
-    });
-  });
-  equal(firstInitializerRunCount, 1, 'first initializer only was run');
-  equal(secondInitializerRunCount, 0, 'first initializer only was run');
-  Ember.run(function() {
-    var secondApp = SecondApp.create({
-      router: false,
-      rootElement: '#qunit-fixture #second'
-    });
-  });
-  equal(firstInitializerRunCount, 1, 'second initializer only was run');
-  equal(secondInitializerRunCount, 1, 'second initializer only was run');
-});

packages/ember-metal/lib/mixin.js

@@ -137,9 +137,7 @@ function applyConcatenatedProperties(obj, key, value, values) {
       return Ember.makeArray(baseValue).concat(value);
     }
   } else {
-    // Make sure this mixin has its own array so it is not
-    // accidentally mutated by another child's interactions
-    return Ember.makeArray(value).slice();
+    return Ember.makeArray(value);
   }
 }