DevTools: Freshen up popover styles.

Source/devtools/front_end/inspectorStyle.css

 /*
  * Copyright (C) 2006, 2007, 2008 Apple Inc.  All rights reserved.
  * Copyright (C) 2009 Anthony Ricaud <rik@webkit.org>
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
@@ skipping 2365 matching lines @@
 
 .source-frame-popover-title {
     text-overflow: ellipsis;
     overflow: hidden;
     white-space: nowrap;
     font-weight: bold;
     padding-left: 18px;
 }
 
 .source-frame-popover-tree {
-    border-top: 1px solid rgb(194, 194, 147);
+    border-top: 1px solid rgb(184, 184, 184);
     overflow: auto;
     position: absolute;
     top: 15px;
     bottom: 0;
     left: 0;
     right: 0;
 }
 
 .source-frame-eval-expression {
     outline: 1px solid rgb(163, 41, 34);
@@ skipping 433 matching lines @@
 }
 
 .custom-popup-vertical-scroll ::-webkit-scrollbar-thumb:vertical:hover {
     -webkit-border-image: url(Images/thumbHoverVert.png) 11 0 11 0;
 }
 
 .custom-popup-vertical-scroll ::-webkit-scrollbar-thumb:vertical:active {
     -webkit-border-image: url(Images/thumbActiveVert.png) 11 0 11 0;
 }
 
-.custom-popup-vertical-scroll ::-webkit-scrollbar-track-piece:vertical:start {
-    margin-top: 5px;
+.custom-popup-vertical-scroll ::-webkit-scrollbar-track-piece:vertical:decrement {
 }
 
-.custom-popup-vertical-scroll ::-webkit-scrollbar-track-piece:vertical:end {
-    margin-bottom: 5px;
-}
-
-.custom-popup-vertical-scroll ::-webkit-scrollbar-track-piece:vertical:end:corner-present {
-    margin-bottom: 4px;
-}
-
-.custom-popup-vertical-scroll ::-webkit-scrollbar-track-piece:vertical:decrement {
-    -webkit-border-image: url(Images/trackVert.png) 11 0 11 0;
-    border-color: transparent;
-    border-width: 11px 0 0 0;
-}
-
-.custom-popup-vertical-scroll ::-webkit-scrollbar-track-piece:vertical:increment {
-    -webkit-border-image: url(Images/trackVert.png) 11 0 11 0;
-    border-color: transparent;
-    border-width: 0 0 11px 0;
+.custom-popup-vertical-scroll ::-webkit-scrollbar-track:vertical {
+    background: linear-gradient(to right, rgb(80, 80, 80), rgb(192, 192, 192) 25%, rgb(192, 192, 192));
+    border-radius: 5px;
+    margin: 5px;
 }
 
 .console-context {
     max-width: 200px;
 }
 
 .root-view {
     overflow: hidden;
     position: absolute !important;
     left: 0;
@@ skipping 69 matching lines @@
 }
 
 .viewport-control-gap-element {
     color: transparent;
 }
 
 label.checkbox-with-label {
     display: flex;
     -webkit-user-select: none;
 }