Added base template for config ui.

appengine/config_service/ui/bower_components/polymer/lib/utils/mixin.html

+<!--
+@license
+Copyright (c) 2017 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="boot.html">
+
+<script>
+
+(function() {
+
+  'use strict';
+
+  // unique global id for deduping mixins.
+  let dedupeId = 0;
+
+  /**
+   * Given a mixin producing function, memoize applications of mixin to base
+   * @private
+   * @param {Function} mixin Mixin for which to create a caching mixin.
+   * @return {Function} Returns a mixin which when applied multiple times to the
+   * same base will always return the same extended class.
+   */
+  function cachingMixin(mixin) {
+    return function(base) {
+      if (!mixin.__mixinApplications) {
+        mixin.__mixinApplications = new WeakMap();
+      }
+      let map = mixin.__mixinApplications;
+      let application = map.get(base);
+      if (!application) {
+        application = mixin(base);
+        map.set(base, application);
+      }
+      return application;
+    };
+  }
+
+  /**
+   * Wraps an ES6 class expression mixin such that the mixin is only applied
+   * if it has not already been applied its base argument.  Also memoizes mixin
+   * applications.
+   *
+   * @memberof Polymer
+   * @param {Function} mixin ES6 class expression mixin to wrap
+   * @return {Function} Wrapped mixin that deduplicates and memoizes
+   *   mixin applications to base
+   */
+  Polymer.dedupingMixin = function(mixin) {
+    mixin = cachingMixin(mixin);
+    // maintain a unique id for each mixin
+    mixin.__dedupeId = ++dedupeId;
+    return function(base) {
+      let baseSet = base.__mixinSet;
+      if (baseSet && baseSet[mixin.__dedupeId]) {
+        return base;
+      }
+      let extended = mixin(base);
+      // copy inherited mixin set from the extended class, or the base class
+      // NOTE: we avoid use of Set here because some browser (IE11)
+      // cannot extend a base Set via the constructor.
+      extended.__mixinSet =
+        Object.create(extended.__mixinSet || baseSet || null);
+      extended.__mixinSet[mixin.__dedupeId] = true;
+      return extended;
+    }
+  };
+
+})();
+
+</script>