Devtools UI: Add high DPI chevron overflow icon

Source/devtools/front_end/promises/promisePane.css

 /*
  * Copyright 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.
  */
 
 .promises .data-grid {
     border: none;
     flex: 1 1;
 }
@@ skipping 44 matching lines @@
 
 .promises .status {
     -webkit-mask-image: url(Images/toolbarButtonGlyphs.png);
     -webkit-mask-size: 352px 168px;
     -webkit-mask-position: -294px -26px;
     background-color: #bbb;
     height: 20px;
     width: 20px;
 }
 
+@media (-webkit-min-device-pixel-ratio: 1.5) {
+.promises .status {
+    -webkit-mask-image: url(Images/toolbarButtonGlyphs_2x.png);
+}
+} /* media */
+
 .promises .status.rejected {
     background-color: rgb(216, 0, 0);
 }
 
 .promises .status.resolved {
     background-color: #696;
 }
 
 .promises-filters-header {
     flex: 0 0 23px;
     overflow: hidden;
 }
 
 .promises-filter-status {
     flex: 0 0 23px;
     padding-left: 18px;
     color: rgb(128, 128, 128);
     font-style: italic;
 }
 .promises-filter-status .link:hover {
     color: rgb(15%, 15%, 15%);
 }
 .promises-filter-status .link {
     color: rgb(33%, 33%, 33%);
 }