Fix regression: background artifact for origin glyphs of the '.security-property-unknown' persuasio…

third_party/WebKit/Source/devtools/front_end/security/sidebar.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.
  */
 
 .tree-outline {
     padding: 0;
 }
 
 .tree-outline:focus li.selected .lock-icon-neutral {
@@ skipping 31 matching lines @@
 .tree-outline .sidebar-tree-section + .children > .sidebar-tree-item {
     padding-left: 16px;
 }
 
 .tree-outline .sidebar-tree-item .lock-icon,
 .tree-outline .sidebar-tree-item .security-property {
     float: left;
     margin-right: 2px;
 }
 
-.tree-outline .security-sidebar-tree-item.selected .icon {
+.tree-outline .security-sidebar-tree-item.selected .icon:not(.security-property-unknown) {
     background-image: none;
     background-color: #fff;
 }
 
 .tree-outline li.selected .lock-icon-neutral {
     background-image: none;
     background-color: #5a5a5a;
     -webkit-mask-image: url(Images/securityStateNeutral.svg);
     -webkit-mask-size: cover;
 }
 
 .tree-outline .security-sidebar-tree-item.selected .security-property-insecure {
     -webkit-mask-image: url(Images/securityPropertyInsecure.svg);
 }
 
 .security-sidebar-tree-item.selected .security-property-neutral,
 .security-sidebar-tree-item.selected .security-property-warning {
     -webkit-mask-image: url(Images/securityPropertyWarning.svg);
 }
 
 .security-sidebar-tree-item.selected .security-property-secure {
     -webkit-mask-image: url(Images/securityPropertySecure.svg);
 }