Pass in the prototype to CreateApiFunction rather than setting it on the result.

src/runtime.cc

 // Copyright 2012 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 2116 matching lines @@
   CONVERT_ARG_HANDLE_CHECKED(String, flags, 2);
   Handle<Object> result;
   ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
       isolate, result, RegExpImpl::Compile(re, pattern, flags));
   return *result;
 }
 
 
 RUNTIME_FUNCTION(Runtime_CreateApiFunction) {
   HandleScope scope(isolate);
-  ASSERT(args.length() == 1);
+  ASSERT(args.length() == 2);
   CONVERT_ARG_HANDLE_CHECKED(FunctionTemplateInfo, data, 0);
-  return *isolate->factory()->CreateApiFunction(data);
+  CONVERT_ARG_HANDLE_CHECKED(Object, prototype, 1);
+  return *isolate->factory()->CreateApiFunction(data, prototype);
 }
 
 
 RUNTIME_FUNCTION(Runtime_IsTemplate) {
   SealHandleScope shs(isolate);
   ASSERT(args.length() == 1);
   CONVERT_ARG_HANDLE_CHECKED(Object, arg, 0);
   bool result = arg->IsObjectTemplateInfo() || arg->IsFunctionTemplateInfo();
   return isolate->heap()->ToBoolean(result);
 }
@@ skipping 648 matching lines @@
 }
 
 
 static Handle<JSFunction> InstallBuiltin(Isolate* isolate,
                                          Handle<JSObject> holder,
                                          const char* name,
                                          Builtins::Name builtin_name) {
   Handle<String> key = isolate->factory()->InternalizeUtf8String(name);
   Handle<Code> code(isolate->builtins()->builtin(builtin_name));
   Handle<JSFunction> optimized =
-      isolate->factory()->NewFunction(key,
+      isolate->factory()->NewFunction(MaybeHandle<Object>(),
+                                      key,
                                       JS_OBJECT_TYPE,
                                       JSObject::kHeaderSize,
                                       code,
                                       false);
   optimized->shared()->DontAdaptArguments();
   JSReceiver::SetProperty(holder, key, optimized, NONE, STRICT).Assert();
   return optimized;
 }
 
 
@@ skipping 12324 matching lines @@
   }
   return NULL;
 }
 
 
 const Runtime::Function* Runtime::FunctionForId(Runtime::FunctionId id) {
   return &(kIntrinsicFunctions[static_cast<int>(id)]);
 }
 
 } }  // namespace v8::internal