DevTools: Add hover affordance for checkboxes

Source/devtools/front_end/inspector.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 21 matching lines @@
     outline: auto 5px -webkit-focus-ring-color;
 }
 
 input[type="checkbox"] {
     height: 13px;
     width: 13px;
     margin: auto 3px;
     flex-shrink: 0;
 }
 
+label:hover {
+    cursor: pointer;
+}
+
+label:hover input {
+    box-shadow: 0 0 3px highlight;
+}
+
+fieldset[disabled] label:hover input {
+    box-shadow: none;
+}
+
 .fill {
     position: absolute;
     top: 0;
     left: 0;
     right: 0;
     bottom: 0;
 }
 
 .view {
     position: relative;
@@ skipping 2782 matching lines @@
 }
 
 .root-view > .split-view > .split-view-sidebar {
     position: relative;
 }
 
 select.drop-down-menu {
     border: none;
     -webkit-appearance: none;
 }