Show function <name>() { [native code] } for built-in classes

src/v8natives.js

 // Copyright 2012 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.
 
 // This file relies on the fact that the following declarations have been made
 // in runtime.js:
 // var $Object = global.Object;
 // var $Boolean = global.Boolean;
 // var $Number = global.Number;
 // var $Function = global.Function;
@@ skipping 1720 matching lines @@
 
   %SetInlineBuiltinFlag(NumberIsNaN);
 }
 
 SetUpNumber();
 
 
 // ----------------------------------------------------------------------------
 // Function
 
+function NativeCodeFunctionSourceString(func) {
+  var name = %FunctionGetName(func);
+  if (name) {
+    // Mimic what KJS does.
+    return 'function ' + name + '() { [native code] }';
+  }
+
+  return 'function () { [native code] }';
+}
+
 function FunctionSourceString(func) {
   while (%IsJSFunctionProxy(func)) {
     func = %GetCallTrap(func);
   }
 
   if (!IS_FUNCTION(func)) {
     throw MakeTypeError(kNotGeneric, 'Function.prototype.toString');
   }
 
+  if (%FunctionIsBuiltin(func)) {
+    return NativeCodeFunctionSourceString(func);
+  }
+
   var classSource = %ClassGetSourceCode(func);
   if (IS_STRING(classSource)) {
     return classSource;
   }
 
   var source = %FunctionGetSourceCode(func);
-  if (!IS_STRING(source) || %FunctionIsBuiltin(func)) {
-    var name = %FunctionGetName(func);
-    if (name) {
-      // Mimic what KJS does.
-      return 'function ' + name + '() { [native code] }';
-    } else {
-      return 'function () { [native code] }';
-    }
+  if (!IS_STRING(source)) {
+    return NativeCodeFunctionSourceString(func);
   }
 
   if (%FunctionIsArrow(func)) {
     return source;
   }
 
   var name = %FunctionNameShouldPrintAsAnonymous(func)
       ? 'anonymous'
       : %FunctionGetName(func);
 
@@ skipping 131 matching lines @@
   }
   if (!IS_SPEC_FUNCTION(method)) {
     throw MakeTypeError(kNotIterable, obj);
   }
   var iterator = %_CallFunction(obj, method);
   if (!IS_SPEC_OBJECT(iterator)) {
     throw MakeTypeError(kNotAnIterator, iterator);
   }
   return iterator;
 }