Remove third_party/polymer from .gitignore

third_party/polymer/v1_0/components/neon-animation/animations/cascaded-animation.html

-<!--
-@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.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="../../polymer/polymer.html">
-<link rel="import" href="../neon-animation-behavior.html">
-<link rel="import" href="../web-animations.html">
-
-<!--
-`<cascaded-animation>` applies an animation on an array of elements with a delay between each.
-the delay defaults to 50ms.
-
-Configuration:
-```
-{
-  name: 'cascaded-animation',
-  animation: <animation-name>,
-  nodes: <array-of-nodes>,
-  nodedelay: <node-delay-in-ms>,
-  timing: <animation-timing>
-}
-```
--->
-
-<script>
-
-  Polymer({
-
-    is: 'cascaded-animation',
-
-    behaviors: [
-      Polymer.NeonAnimationBehavior
-    ],
-
-    properties: {
-
-      /** @type {!Polymer.IronMeta} */
-      _animationMeta: {
-        type: Object,
-        value: function() {
-          return new Polymer.IronMeta({type: 'animation'});
-        }
-      }
-
-    },
-
-    /**
-     * @param {{
-     *   animation: string,
-     *   nodes: !Array<!Element>,
-     *   nodeDelay: (number|undefined),
-     *   timing: (Object|undefined)
-     *  }} config
-     */
-    configure: function(config) {
-      var animationConstructor = /** @type {Function} */ (
-          this._animationMeta.byKey(config.animation));
-      if (!animationConstructor) {
-        console.warn(this.is + ':', 'constructor for', config.animation, 'not found!');
-        return;
-      }
-
-      this._animations = [];
-      var nodes = config.nodes;
-      var effects = [];
-      var nodeDelay = config.nodeDelay || 50;
-
-      config.timing = config.timing || {};
-      config.timing.delay = config.timing.delay || 0;
-
-      var oldDelay = config.timing.delay;
-      for (var node, index = 0; node = nodes[index]; index++) {
-        config.timing.delay += nodeDelay;
-        config.node = node;
-
-        var animation = new animationConstructor();
-        var effect = animation.configure(config);
-
-        this._animations.push(animation);
-        effects.push(effect);
-      }
-      config.timing.delay = oldDelay;
-
-      this._effect = new GroupEffect(effects);
-      return this._effect;
-    },
-
-    complete: function() {
-      for (var animation, index = 0; animation = this._animations[index]; index++) {
-        animation.complete(animation.config);
-      }
-    }
-
-  });
-
-</script>