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

third_party/polymer/v1_0/components/iron-pages/iron-pages.html

Index: third_party/polymer/v1_0/components/iron-pages/iron-pages.html
diff --git a/third_party/polymer/v1_0/components/iron-pages/iron-pages.html b/third_party/polymer/v1_0/components/iron-pages/iron-pages.html
index 6fe2f482845e12ac7960c358e3f8a9d6c4bf073d..1753f0eb177068b874c1d4824e2d159be18ac52d 100644
--- a/third_party/polymer/v1_0/components/iron-pages/iron-pages.html
+++ b/third_party/polymer/v1_0/components/iron-pages/iron-pages.html
@@ -71,6 +71,18 @@ Example:
       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)'
     ],