Remove third_party/polymer from .gitignore

third_party/polymer/v1_0/components/iron-media-query/iron-media-query.html

-<!--
-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">
-
-<!--
-`iron-media-query` can be used to data bind to a CSS media query.
-The `query` property is a bare CSS media query.
-The `query-matches` property is a boolean representing whether the page matches that media query.
-
-Example:
-
-    <iron-media-query query="(min-width: 600px)" query-matches="{{queryMatches}}"></iron-media-query>
-
-@group Iron Elements
-@demo demo/index.html
-@hero hero.svg
-@element iron-media-query
--->
-
-<script>
-
-  Polymer({
-
-    is: 'iron-media-query',
-
-    properties: {
-
-      /**
-       * The Boolean return value of the media query.
-       */
-      queryMatches: {
-        type: Boolean,
-        value: false,
-        readOnly: true,
-        notify: true
-      },
-
-      /**
-       * The CSS media query to evaluate.
-       */
-      query: {
-        type: String,
-        observer: 'queryChanged'
-      }
-
-    },
-
-    created: function() {
-      this._mqHandler = this.queryHandler.bind(this);
-    },
-
-    queryChanged: function(query) {
-      if (this._mq) {
-        this._mq.removeListener(this._mqHandler);
-      }
-      if (query[0] !== '(') {
-        query = '(' + query + ')';
-      }
-      this._mq = window.matchMedia(query);
-      this._mq.addListener(this._mqHandler);
-      this.queryHandler(this._mq);
-    },
-
-    queryHandler: function(mq) {
-      this._setQueryMatches(mq.matches);
-    }
-
-  });
-
-</script>