Update bower.json for Polymer elements and add PRESUBMIT.py

third_party/polymer/v1_0/components/paper-button/paper-button.html

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 @license
 Copyright (c) 2015 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
 The complete set of authors may be found at http://polymer.github.io/AUTHORS
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@@ skipping 13 matching lines @@
 Example:
 
     <paper-button>flat button</paper-button>
     <paper-button raised>raised button</paper-button>
     <paper-button noink>No ripple effect</paper-button>
 
 You may use custom DOM in the button body to create a variety of buttons. For example, to
 create a button with an icon and some text:
 
     <paper-button>
-      <core-icon icon="favorite"></core-icon>
+      <iron-icon icon="favorite"></iron-icon>
       custom button content
     </paper-button>
 
 ### Styling
 
 Style the button with CSS as you would a normal DOM element.
 
     /* make #my-button green with yellow text */
     #my-button {
         background: green;
@@ skipping 123 matching lines @@
     _computeContentClass: function(receivedFocusFromKeyboard) {
       var className = 'content ';
       if (receivedFocusFromKeyboard) {
         className += ' keyboard-focus';
       }
       return className;
     }
   });
 
 </script>