DevTools: Migrate from -webkit-user-modify to contenteditable

third_party/WebKit/Source/devtools/front_end/sources/sourcesView.css

 /*
  * Copyright (C) 2013 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 71 matching lines @@
     cursor: default;
     margin: 0 0 2px 0;
 }
 
 #source-frame-breakpoint-condition {
     margin: 0;
     border: 1px inset rgb(190, 190, 190) !important;
     width: 100%;
     box-shadow: none !important;
     outline: none !important;
-    -webkit-user-modify: read-write;
 }
 
 @-webkit-keyframes source-frame-value-update-highlight-animation {
     from {
         background-color: inherit;
         color: inherit;
     }
     10% {
         background-color: rgb(158, 54, 153);
         color: white;
@@ skipping 61 matching lines @@
     90% { background-color: rgba(158, 54, 153, 0); }
     to { background-color: transparent; }
 }
 
 @keyframes source-line-modification-foreground-fadeout {
     from { color: white; }
     50% { color: white; }
     90% { color: intial; }
     to { color: intial; }
 }