MAGETWO-38867: Create mixin for declarative widget description

Author: Ihor Melnychenko

lib/web/mage/apply/main.js

@@ -42,9 +42,9 @@ define([
         var configStack = {},
             element = itemContainer.el;
 
-        _.each(mixinList, function (mixin, componentName) {
+        _.each(mixinList, function (mixinArray, componentName) {
             configStack = itemContainer.data[componentName];
-            require(mixin, function(){
+            require(mixinArray, function(){
                 for (var i = 0, len = arguments.length; i < len; i++){
                     configStack = arguments[i](configStack, element);
                 }