DevTools: Show CSS variables in the inherited properties cascade

third_party/WebKit/Source/devtools/front_end/sdk/CSSMetadata.js

 /*
  * Copyright (C) 2010 Nikita Vasilyev. All rights reserved.
  * Copyright (C) 2010 Joseph Pecoraro. All rights reserved.
  * Copyright (C) 2010 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
@@ skipping 162 matching lines @@
       return true;
     return this._valuesSet.has(propertyName);
   }
 
   /**
    * @param {string} propertyName
    * @return {boolean}
    */
   isPropertyInherited(propertyName) {
     propertyName = propertyName.toLowerCase();
-    return this._inherited.has(this.canonicalPropertyName(propertyName)) || this._inherited.has(propertyName);
+    return propertyName.startsWith('--') || this._inherited.has(this.canonicalPropertyName(propertyName)) ||
+        this._inherited.has(propertyName);
   }
 
   /**
    * @param {string} propertyName
    * @return {!Array<string>}
    */
   propertyValues(propertyName) {
     var acceptedKeywords = ['inherit', 'initial'];
     propertyName = propertyName.toLowerCase();
     var unprefixedName = propertyName.replace(/^-webkit-/, '');
@@ skipping 755 matching lines @@
   'widows': 115,
   'width': 268,
   'will-change': 74,
   'word-break': 166,
   'word-spacing': 157,
   'word-wrap': 197,
   'writing-mode': 41,
   'z-index': 239,
   'zoom': 200
 };