DevTools: migrate TabbedPane chevron over to UI.Icon.

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

 /*
  * Copyright (C) 2006, 2007, 2008 Apple Inc.  All rights reserved.
  * Copyright (C) 2009 Anthony Ricaud <rik@webkit.org>
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
  * 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
@@ skipping 128 matching lines @@
     float: left;
     position: relative;
     vertical-align: bottom;
     line-height: 24px;
     opacity: 0.8;
     color: inherit;
     font-size: 133%;
     cursor: pointer;
 }
 
-.tabbed-pane-header-tabs-drop-down-container > .glyph {
-    height: 26px;
+.tabbed-pane-header-tabs-drop-down-container > .chevron-icon {
     background-color: hsla(0,0%,20%,1);
-    -webkit-mask-image: url(Images/toolbarButtonGlyphs.png);
-    -webkit-mask-position: -68px -143px;
-    -webkit-mask-size: 352px 168px;
-    width: 24px;
+    display: block;
 }
 
-@media (-webkit-min-device-pixel-ratio: 1.1) {
-.tabbed-pane-header-tabs-drop-down-container > .glyph {
-    -webkit-mask-image: url(Images/toolbarButtonGlyphs_2x.png);
-}
-} /* media */
-
 .tabbed-pane-header-tabs-drop-down-container:hover {
     background-color: rgb(229, 229, 229);
 }
 
 .tabbed-pane-header-tabs-drop-down-container.measuring {
     visibility: hidden;
 }
 
 .tabbed-pane-header-tabs-drop-down-container:hover {
     opacity: 1.0;
@@ skipping 103 matching lines @@
 
 .tabbed-pane-left-toolbar {
     margin-right: -4px;
     flex: none;
 }
 
 .tabbed-pane-right-toolbar {
     margin-left: -4px;
     flex: none;
 }