DevTools: convert a few more icons to UI.Icon.

third_party/WebKit/Source/devtools/front_end/network/blockedURLsPane.css

 /*
  * Copyright (c) 2015 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.
  */
 
 .blocked-urls-pane {
     overflow: hidden;
 }
 
@@ skipping 45 matching lines @@
 }
 
 .blocked-url-text {
     white-space: nowrap;
     text-overflow: ellipsis;
     overflow: hidden;
     flex: auto;
     margin-right: 5px;
 }
 
-.blocked-url .remove-button {
-    width: 13px;
-    height: 13px;
-    background-image: url(Images/toolbarButtonGlyphs.png);
-    background-size: 352px 168px;
-    background-position: -175px -96px;
+.remove-icon {
+    opacity: 0.7;
     visibility: hidden;
-    flex: none;
-    opacity: 0.7;
-    cursor: default;
 }
 
-@media (-webkit-min-device-pixel-ratio: 1.1) {
-.blocked-url .remove-button {
-    background-image: url(Images/toolbarButtonGlyphs_2x.png);
+.blocked-url .remove-icon:hover {
+    opacity: 1.0;
 }
-} /* media */
 
-.blocked-url:hover .remove-button {
+.blocked-url:hover .remove-icon {
     visibility: visible;
 }
-
-.blocked-url .remove-button:hover {
-    opacity: 1.0;
-}