add a default value for return value

src/arguments.h

Index: src/arguments.h
diff --git a/src/arguments.h b/src/arguments.h
index e13ddc9ec83f0f69e1bdb53d00a18ca9b5522310..6ef19c5056d9de53b46efb488ab74a822c37b1d9 100644
--- a/src/arguments.h
+++ b/src/arguments.h
@@ -253,6 +253,8 @@ class PropertyCallbackArguments
     values[T::kHolderIndex] = holder;
     values[T::kDataIndex] = data;
     values[T::kIsolateIndex] = reinterpret_cast<Object*>(isolate);
+    values[T::kReturnValueDefaultValueIndex] =

[Sven Panne, 2013/06/10 07:24:00]

How do we make sure that the hole never escapes to JavaScript land? I can't
immediately see why this is guaranteed, so at least a comment might be
appropriate.

+        isolate->heap()->the_hole_value();
     values[T::kReturnValueIndex] = isolate->heap()->the_hole_value();
     ASSERT(values[T::kHolderIndex]->IsHeapObject());
     ASSERT(values[T::kIsolateIndex]->IsSmi());
@@ -313,6 +315,8 @@ class FunctionCallbackArguments
     values[T::kCalleeIndex] = callee;
     values[T::kHolderIndex] = holder;
     values[T::kIsolateIndex] = reinterpret_cast<internal::Object*>(isolate);
+    values[T::kReturnValueDefaultValueIndex] =

[Sven Panne, 2013/06/10 07:24:00]

Same here.

+        isolate->heap()->the_hole_value();
     values[T::kReturnValueIndex] = isolate->heap()->the_hole_value();
     ASSERT(values[T::kCalleeIndex]->IsJSFunction());
     ASSERT(values[T::kHolderIndex]->IsHeapObject());