DevTools: [Elements] Highlight DOM updates

Source/devtools/front_end/elements/elementsTreeOutline.css

 /*
  * Copyright (c) 2014 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.
  */
 
 .outline-disclosure {
     width: 100%;
     display: inline-block;
     line-height: normal;
@@ skipping 253 matching lines @@
     cursor: default !important;
 }
 
 .nowrap, .nowrap .li {
     white-space: pre !important;
 }
 
 .outline-disclosure .nowrap li {
     word-wrap: normal;
 }
+
+/* DOM update highlight */
+
+@-webkit-keyframes dom-update-highlight-animation {
+    from { background-color: rgb(255, 242, 114); }
+    90% { background-color: rgb(255, 242, 114); }
+    to { background-color: inherit; }
+}
+
+.dom-update-highlight {
+    -webkit-animation: dom-update-highlight-animation 2s 1;
+    color: red !important;
+}