Improve performance of Error.stack when stack contains local functions....

src/messages.js

 // Copyright 2006-2008 the V8 project authors. 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
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 813 matching lines @@
           fileLocation += ":" + columnNumber;
         }
       }
     }
   }
   if (!fileLocation) {
     fileLocation = "unknown source";
   }
   var line = "";
   var functionName = frame.getFunction().name;
-  var methodName = frame.getMethodName();
   var addPrefix = true;
   var isConstructor = frame.isConstructor();
   var isMethodCall = !(frame.isToplevel() || isConstructor);
   if (isMethodCall) {
+    var methodName = frame.getMethodName();
     line += frame.getTypeName() + ".";
     if (functionName) {
       line += functionName;
       if (methodName && (methodName != functionName)) {
         line += " [as " + methodName + "]";
       }
     } else {
       line += methodName || "<anonymous>";
     }
   } else if (isConstructor) {
@@ skipping 130 matching lines @@
     return this.name + ": " + FormatMessage({ type: type, args: this.arguments });
   }
   var message = this.message;
   return this.name + (message ? (": " + message) : "");
 }, DONT_ENUM);
 
 
 // Boilerplate for exceptions for stack overflows. Used from
 // Top::StackOverflow().
 const kStackOverflowBoilerplate = MakeRangeError('stack_overflow', []);