Add paper-dropdown and paper-dropdown-menu and run reproduce.sh

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

 /*
  * @license
  * 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 {
+  position: relative;
   display: inline-block;
-  text-align: inherit;
-  position: relative;
-  width: 20em;
+  background-color: #fff;
+  -moz-user-select: none;
+  -ms-user-select: none;
+  -webkit-user-select: none;
+  user-select: none;
+  cursor: pointer;
+  padding: 0.75em 0;
 }
 
-:host:hover {
-  cursor: text;
+#control {
+  box-sizing: border-box;
+  max-height: 2em;
+  color: #757575;
+  border-bottom: 1px solid #757575;
 }
 
-input,
-textarea {
-  font: inherit;
-  color: inherit;
-  width: 100%;
-  margin: 0;
-  padding: 0;
-  background-color: transparent;
-  border: none;
-  outline: none;
-  width: 100%;
+#control[selected] {
+  color: #000;
 }
 
-textarea {
-  resize: none;
+#control > div {
+  padding: 0.5em 0 0.25em;
+  overflow: hidden;
+  /* FIXME not working for some reason */
+  white-space: nowrap;
+  text-overflow: ellipsis;
 }
 
-textarea[rows=fit] {
-  height: 100%;
+core-icon {
+  margin: 0.3em 0 0.2em 0.25em;
 }