Fix detection of BUILTIN functions

test/inspector/protocol-test.js

 // Copyright 2016 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 InspectorTest = {};
 InspectorTest._dispatchTable = new Map();
 InspectorTest._requestId = 0;
 InspectorTest._dumpInspectorProtocolMessages = false;
 InspectorTest._eventHandler = {};
 
@@ skipping 78 matching lines @@
   function dumpItems(object, prefix, firstLinePrefix)
   {
     prefix = prefix || "";
     firstLinePrefix = firstLinePrefix || prefix;
     lines.push(firstLinePrefix + "[");
     for (var i = 0; i < object.length; ++i)
       dumpValue(object[i], "    " + prefix, "    " + prefix + "[" + i + "] : ");
     lines.push(prefix + "]");
   }
 
-  dumpValue(object, "", title);
+  dumpValue(object, "", title || "");
   InspectorTest.log(lines.join("\n"));
 }
 
 InspectorTest.completeTest = function()
 {
   Protocol.Debugger.disable().then(() => quit());
 }
 
 InspectorTest.completeTestAfterPendingTimeouts = function()
 {
@@ skipping 94 matching lines @@
       var eventName = messageObject["method"];
       var eventHandler = InspectorTest._eventHandler[eventName];
       if (eventHandler)
         eventHandler(messageObject);
     }
   } catch (e) {
     InspectorTest.log("Exception when dispatching message: " + e + "\n" + e.stack + "\n message = " + JSON.stringify(messageObject, null, 2));
     InspectorTest.completeTest();
   }
 }