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

src/messages.js

Index: src/messages.js
===================================================================
--- src/messages.js	(revision 5295)
+++ src/messages.js	(working copy)
@@ -831,11 +831,11 @@
   }
   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;