Make Function.length and Function.name configurable properties.

src/bootstrapper.cc

Index: src/bootstrapper.cc
diff --git a/src/bootstrapper.cc b/src/bootstrapper.cc
index f27ca7ab8d687ac4f9de190edbdf6f247a7f7c21..7a279f66ca633b7a433186e4ab50d6135b529294 100644
--- a/src/bootstrapper.cc
+++ b/src/bootstrapper.cc
@@ -396,31 +396,32 @@ void Genesis::SetFunctionInstanceDescriptor(
   if (prototypeMode != DONT_ADD_PROTOTYPE) {
     prototype = factory()->NewForeign(&Accessors::FunctionPrototype);
   }
-  PropertyAttributes attribs = static_cast<PropertyAttributes>(
+  PropertyAttributes ro_attribs = static_cast<PropertyAttributes>(
       DONT_ENUM | DONT_DELETE | READ_ONLY);
+  PropertyAttributes roc_attribs = static_cast<PropertyAttributes>(
+      DONT_ENUM | READ_ONLY);
   map->set_instance_descriptors(*descriptors);
 
   {  // Add length.
-    CallbacksDescriptor d(*factory()->length_string(), *length, attribs);
+    CallbacksDescriptor d(*factory()->length_string(), *length, roc_attribs);
     map->AppendDescriptor(&d, witness);
   }
   {  // Add name.
-    CallbacksDescriptor d(*factory()->name_string(), *name, attribs);
+    CallbacksDescriptor d(*factory()->name_string(), *name, roc_attribs);
     map->AppendDescriptor(&d, witness);
   }
   {  // Add arguments.
-    CallbacksDescriptor d(*factory()->arguments_string(), *args, attribs);
+    CallbacksDescriptor d(*factory()->arguments_string(), *args, ro_attribs);
     map->AppendDescriptor(&d, witness);
   }
   {  // Add caller.
-    CallbacksDescriptor d(*factory()->caller_string(), *caller, attribs);
+    CallbacksDescriptor d(*factory()->caller_string(), *caller, ro_attribs);
     map->AppendDescriptor(&d, witness);
   }
   if (prototypeMode != DONT_ADD_PROTOTYPE) {
     // Add prototype.
-    if (prototypeMode == ADD_WRITEABLE_PROTOTYPE) {
-      attribs = static_cast<PropertyAttributes>(attribs & ~READ_ONLY);
-    }
+    PropertyAttributes attribs = (prototypeMode == ADD_WRITEABLE_PROTOTYPE)
+        ? static_cast<PropertyAttributes>(ro_attribs & ~READ_ONLY) : ro_attribs;
     CallbacksDescriptor d(*factory()->prototype_string(), *prototype, attribs);
     map->AppendDescriptor(&d, witness);
   }
@@ -538,14 +539,16 @@ void Genesis::SetStrictFunctionInstanceDescriptor(
       static_cast<PropertyAttributes>(DONT_ENUM | DONT_DELETE);
   PropertyAttributes ro_attribs =
       static_cast<PropertyAttributes>(DONT_ENUM | DONT_DELETE | READ_ONLY);
+  PropertyAttributes roc_attribs =
+      static_cast<PropertyAttributes>(DONT_ENUM | READ_ONLY);
   map->set_instance_descriptors(*descriptors);
 
   {  // Add length.
-    CallbacksDescriptor d(*factory()->length_string(), *length, ro_attribs);
+    CallbacksDescriptor d(*factory()->length_string(), *length, roc_attribs);
     map->AppendDescriptor(&d, witness);
   }
   {  // Add name.
-    CallbacksDescriptor d(*factory()->name_string(), *name, ro_attribs);
+    CallbacksDescriptor d(*factory()->name_string(), *name, roc_attribs);
     map->AppendDescriptor(&d, witness);
   }
   {  // Add arguments.