[MD Bookmarks] Add keyboard navigation and selection to bookmark list.

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

Index: third_party/polymer/v1_0/components-chromium/iron-list/iron-list-extracted.js
diff --git a/third_party/polymer/v1_0/components-chromium/iron-list/iron-list-extracted.js b/third_party/polymer/v1_0/components-chromium/iron-list/iron-list-extracted.js
index c9e0a9fd5330f9f791ccf274c40de7197965a2e5..780e6cb4617dcfdf04eec8a459bbfe14a4b72869 100644
--- a/third_party/polymer/v1_0/components-chromium/iron-list/iron-list-extracted.js
+++ b/third_party/polymer/v1_0/components-chromium/iron-list/iron-list-extracted.js
@@ -1466,6 +1466,10 @@
       return this._physicalIndexForKey[this._collection.getKey(this._getNormalizedItem(idx))];
     },
 
+    focusItem: function(idx) {
+      this._focusPhysicalItem(idx);
+    },
+
     _focusPhysicalItem: function(idx) {
       if (idx < 0 || idx >= this._virtualCount) {
         return;