DevTools: recognize CSSIdentifiers that start with double hyphen

third_party/WebKit/Source/devtools/front_end/components/DOMPresentationUtils.js

 /*
  * Copyright (C) 2011 Google Inc.  All rights reserved.
  * Copyright (C) 2007, 2008 Apple Inc.  All rights reserved.
  * Copyright (C) 2008 Matt Lilek <webkit@mattlilek.com>
  * Copyright (C) 2009 Joseph Pecoraro
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
@@ skipping 397 matching lines @@
     if (/[a-zA-Z0-9_-]/.test(c))
       return true;
     return c.charCodeAt(0) >= 0xA0;
   }
 
   /**
    * @param {string} value
    * @return {boolean}
    */
   function isCSSIdentifier(value) {
-    return /^-?[a-zA-Z_][a-zA-Z0-9_-]*$/.test(value);
+    // Double hyphen prefixes are not allowed by specification, but many sites use it.
+    return /^-{0,2}[a-zA-Z_][a-zA-Z0-9_-]*$/.test(value);
   }
 
   var prefixedOwnClassNamesArray = prefixedElementClassNames(node);
   var needsClassNames = false;
   var needsNthChild = false;
   var ownIndex = -1;
   var elementIndex = -1;
   var siblings = parent.children();
   for (var i = 0; (ownIndex === -1 || !needsNthChild) && i < siblings.length; ++i) {
     var sibling = siblings[i];
@@ skipping 206 matching lines @@
 
   /**
    * @override
    * @param {!SDK.DOMNode} node
    * @return {?{title: string, color: string}}
    */
   decorate(node) {
     return {title: this._title, color: this._color};
   }
 };