Update more-routing for md-settings

third_party/polymer/v0_8/components/more-routing/params.html

+<!--
+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
+The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
+Code distributed by Google as part of the polymer project is also
+subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
+-->
+<link rel="import" href="emitter.html">
+
+<script>
+(function(scope) {
+var MoreRouting = scope.MoreRouting = scope.MoreRouting || {};
+MoreRouting.Params = Params;
+
+/**
+ * A collection of route parameters and their values, with nofications.
+ *
+ * Params prefixed by `__` are reserved.
+ *
+ * @param {!Array<string>} params The keys of the params being managed.
+ * @param {Params=} parent A parent route's params to inherit.
+ * @return {Params}
+ */
+function Params(params, parent) {
+  var model = Object.create(parent || Params.prototype);
+  // We have a different set of listeners at every level of the hierarchy.
+  Object.defineProperty(model, '__listeners', {value: []});
+
+  // We keep all state enclosed within this closure so that inheritance stays
+  // relatively straightfoward.
+  var state = {};
+  _compile(model, params, state);
+
+  return model;
+}
+Params.prototype = Object.create(MoreRouting.Emitter);
+
+// Utility
+
+function _compile(model, params, state) {
+  params.forEach(function(param) {
+    Object.defineProperty(model, param, {
+      get: function() {
+        return state[param];
+      },
+      set: function(value) {
+        if (state[param] === value) return;
+        state[param] = value;
+        model.__notify(param, value);
+      },
+    });
+  });
+}
+
+})(window);
+</script>