Remove Polymer 0.5.

third_party/polymer/components-chromium/paper-dropdown/paper-dropdown-transition.css

-/* Copyright (c) 2014 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 */
-
-:host(.core-transition) #ripple,
-:host(.core-transition) #background {
-  opacity: 0;
-}
-
-:host(.core-transition) #scroller {
-  opacity: 0;
-}