Roll polymer packages to version 0.3.4

pkg/polymer/lib/src/js/polymer/layout.html

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 Copyright (c) 2014 The Polymer Project Authors. All rights reserved.
 This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
 The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
 The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
 Code distributed by Google as part of the polymer project is also
 subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
 -->
 <style shim-shadowdom>
 /*******************************
@@ skipping 139 matching lines @@
 }
 
 /* alignment in cross axis */
 
 html /deep/ [layout][start] {
   -ms-flex-align: start;
   -webkit-align-items: flex-start;
   align-items: flex-start;
 }
 
-html /deep/ [layout][center] {
+html /deep/ [layout][center], html /deep/ [layout][center-center] {
   -ms-flex-align: center;
   -webkit-align-items: center;
   align-items: center;
 }
 
 html /deep/ [layout][end] {
   -ms-flex-align: end;
   -webkit-align-items: flex-end;
   align-items: flex-end;
 }
 
 /* alignment in main axis */
 
 html /deep/ [layout][start-justified] {
   -ms-flex-pack: start;
   -webkit-justify-content: flex-start;
   justify-content: flex-start;
 }
 
-html /deep/ [layout][center-justified] {
+html /deep/ [layout][center-justified], html /deep/ [layout][center-center] {
   -ms-flex-pack: center;
   -webkit-justify-content: center;
   justify-content: center;
 }
 
 html /deep/ [layout][end-justified] {
   -ms-flex-pack: end;
   -webkit-justify-content: flex-end;
   justify-content: flex-end;
 }
@@ skipping 78 matching lines @@
   box-sizing: border-box;
   margin: 1em 0.5em;
   padding: 1em;
   background-color: white;
   -webkit-box-shadow: 0px 0px 0px 1px rgba(0, 0, 0, 0.1);
   box-shadow: 0px 0px 0px 1px rgba(0, 0, 0, 0.1);
   border-radius: 5px 5px 5px 5px;
 }
 
 </style>