Blog post explaining the behavior
carbon-i18n-behavior 
carbon-i18n-behavior adds internationalization support to Polymer elements. The web component is built with Polymer.
To install the element:
bower install carbon-i18n-behavior
Find here more information on generating the requires JS files
This software is licensed under the Apache 2 license, quoted below.
Copyright 2011-2015 Collaborne B.V. <http://github.com/Collaborne/>
Licensed under the Apache License, Version 2.0 (the "License"); you may not
use this file except in compliance with the License. You may obtain a copy of
the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
License for the specific language governing permissions and limitations under
the License.