Update bower.json for Polymer elements and add PRESUBMIT.py

third_party/polymer/v1_0/components/paper-slider/paper-slider.css

 /**
 @license
 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
-The complete set of authors may be found at http://polymer.github.io/AUTHORS
-The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS
+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
+subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
 */
 
 :host {
   display: inline-block;
   width: 200px;
   cursor: default;
   -webkit-user-select: none;
   -moz-user-select: none;
   -ms-user-select: none;
   user-select: none;
@@ skipping 57 matching lines @@
 }
 
 #sliderBar {
   position: absolute;
   top: 15px;
   left: 0;
   height: 2px;
   width: 100%;
   padding: 8px 0;
   margin: -8px 0;
+  background-color: var(--paper-slider-bar-color, transparent);
 }
 
 .ring #sliderBar {
   left: -4px;
   width: calc(100% + 4px);
 }
 
 .ring.expand:not(.pin) #sliderBar {
   left: -14px;
   width: calc(100% + 14px);
@@ skipping 151 matching lines @@
   background-color: var(--paper-slider-disabled-knob-color, --google-grey-500);
 }
 
 .disabled.ring > #sliderKnob > #sliderKnobInner {
   background-color: transparent;
 }
 
 paper-ripple {
   color: var(--paper-slider-knob-color, --google-blue-700);
 }