Previews should exclude a property if its name is a symbol

src/inspector/injected-script-source.js

 /*
  * Copyright (C) 2007 Apple Inc.  All rights reserved.
  * 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:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
@@ skipping 925 matching lines @@
             if (!descriptor.isOwn)
                 continue;
 
             // Ignore computed properties unless they have getters.
             if (!("value" in descriptor)) {
                 if (descriptor.get)
                     this._appendPropertyPreview(preview, { name: name, type: "accessor", __proto__: null }, propertiesThreshold);
                 continue;
             }
 
+            // Never preview symbols.
+            if (descriptor.symbol)
+                continue;
+
             var value = descriptor.value;
             var type = typeof value;
 
             // Never render functions in object preview.
             if (type === "function" && (this.subtype !== "array" || !isUInt32(name)))
                 continue;
 
             // Special-case HTMLAll.
             if (type === "undefined" && injectedScript._isHTMLAllCollection(value))
                 type = "object";
@@ skipping 109 matching lines @@
             return string.substr(0, leftHalf) + "\u2026" + string.substr(string.length - rightHalf, rightHalf);
         }
         return string.substr(0, maxLength) + "\u2026";
     },
 
     __proto__: null
 }
 
 return injectedScript;
 })