[DevTools] Migrate Popover to GlassPane

third_party/WebKit/Source/devtools/front_end/ui/glassPane.css

 /*
  * Copyright 2017 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.
  */
 
 :host {
     position: absolute !important;
     top: 0;
     bottom: 0;
@@ skipping 11 matching lines @@
 :host-context(.no-pointer-events) {
     pointer-events: none;
 }
 
 .widget {
     display: flex;
     background-color: transparent;
     pointer-events: auto;
     flex: none;
 }
+
+.arrow-top {
+    margin-top: -19px;
+    margin-left: -10px;
+}
+
+.arrow-bottom {
+    margin-left: -10px;
+}
+
+.arrow-left {
+    margin-left: -19px;
+    margin-top: -10px;
+}
+
+.arrow-right {
+    margin-top: -10px;
+}
+
+.arrow-none {
+    display: none;
+}
+
+:host-context(.-theme-with-dark-background) .arrow {
+    -webkit-filter: invert(80%);
+}