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

third_party/polymer/v1_0/components/iron-pages/iron-pages.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.txt
 The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
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@@ skipping 53 matching lines @@
 
   Polymer({
 
     is: 'iron-pages',
 
     behaviors: [
       Polymer.IronResizableBehavior,
       Polymer.IronSelectableBehavior
     ],
 
+    properties: {
+
+      // as the selected page is the only one visible, activateEvent
+      // is both non-sensical and problematic; e.g. in cases where a user
+      // handler attempts to change the page and the activateEvent
+      // handler immediately changes it back
+      activateEvent: {
+        value: null
+      }
+
+    },
+
     observers: [
       '_selectedPageChanged(selected)'
     ],
 
     _selectedPageChanged: function(selected, old) {
       this.async(this.notifyResize);
     }
   });
 
 </script>