Added polymer internationalization sample

src/site/samples/polymer_intl/example/polymer_intl.css

 /* Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file */
 /* for details. All rights reserved. Use of this source code is governed by a */
 /* BSD-style license that can be found in the LICENSE file. */
-
 body {
   background-color: #F8F8F8;
   font-family: 'Open Sans', sans-serif;
   font-size: 14px;
   font-weight: normal;
   line-height: 1.2em;
   margin: 15px;
 }
 
-p {
+h1, p {
   color: #333;
 }
 
-#container {
+#sample_container_id {
   width: 100%;
   height: 400px;
+  position: relative;
   border: 1px solid #ccc;
   background-color: #fff;
 }
 
-#summary {
-  float: left;
-}
 
-#notes {
-  float: right;
-  width: 120px;
-  text-align: right;
-}
-
-.error {
-  font-style: italic;
-  color: red;
-}