[DevTools] Extracted EventListenersTreeOutline

Source/devtools/front_end/components/eventListenersTreeOutline.css

+/* Copyright 2015 The Chromium Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+.event-listener-tree li {
+    padding: 2px 0 0 5px;
+}
+
+.event-listener-tree {
+    margin-top: 5px;
+}
+
+.event-listener-tree > li {
+    border-top: 1px solid rgb(231, 231, 231);
+}
+
+.event-listener-tree > li:first-of-type {
+    border-top: none;
+}
+
+.event-listener-tree {
+    padding-left: 0 !important;
+}
+
+.event-listener-tree li.parent::before {
+    top: 0 !important;
+}
+
+.event-listener-tree .name {
+    color: rgb(136, 19, 145);
+}
+
+.event-listener-tree-subtitle {
+    float: right;
+}