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

third_party/polymer/v1_0/components-chromium/iron-pages/iron-pages-extracted.js

Index: third_party/polymer/v1_0/components-chromium/iron-pages/iron-pages-extracted.js
diff --git a/third_party/polymer/v1_0/components-chromium/iron-pages/iron-pages-extracted.js b/third_party/polymer/v1_0/components-chromium/iron-pages/iron-pages-extracted.js
index 503d9b5c10c875f47a8bd5bdf2ae315de3cfebb5..c175b14c7f5abe74bc8d591e256e7e03c59096d4 100644
--- a/third_party/polymer/v1_0/components-chromium/iron-pages/iron-pages-extracted.js
+++ b/third_party/polymer/v1_0/components-chromium/iron-pages/iron-pages-extracted.js
@@ -9,6 +9,18 @@
       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)'
     ],