Add checks to runtime functions.

src/objects.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 7515 matching lines @@
         heap->isolate()->context()->native_context()->
             initial_object_prototype();
   } else {
     map()->set_non_instance_prototype(false);
   }
 
   return SetInstancePrototype(construct_prototype);
 }
 
 
-Object* JSFunction::RemovePrototype() {
+void JSFunction::RemovePrototype() {
   Context* native_context = context()->native_context();
   Map* no_prototype_map = shared()->is_classic_mode()
       ? native_context->function_without_prototype_map()
       : native_context->strict_mode_function_without_prototype_map();
 
-  if (map() == no_prototype_map) {
-    // Be idempotent.
-    return this;
-  }
+  if (map() == no_prototype_map) return;
 
   ASSERT(map() == (shared()->is_classic_mode()
                    ? native_context->function_map()
                    : native_context->strict_mode_function_map()));
 
   set_map(no_prototype_map);
   set_prototype_or_initial_map(no_prototype_map->GetHeap()->the_hole_value());
-  return this;
 }
 
 
-Object* JSFunction::SetInstanceClassName(String* name) {
+void JSFunction::SetInstanceClassName(String* name) {
   shared()->set_instance_class_name(name);
-  return this;
 }
 
 
 void JSFunction::PrintName(FILE* out) {
   SmartArrayPointer<char> name = shared()->DebugName()->ToCString();
   PrintF(out, "%s", *name);
 }
 
 
 Context* JSFunction::NativeContextFromLiterals(FixedArray* literals) {
@@ skipping 5646 matching lines @@
   set_year(Smi::FromInt(year), SKIP_WRITE_BARRIER);
   set_month(Smi::FromInt(month), SKIP_WRITE_BARRIER);
   set_day(Smi::FromInt(day), SKIP_WRITE_BARRIER);
   set_weekday(Smi::FromInt(weekday), SKIP_WRITE_BARRIER);
   set_hour(Smi::FromInt(hour), SKIP_WRITE_BARRIER);
   set_min(Smi::FromInt(min), SKIP_WRITE_BARRIER);
   set_sec(Smi::FromInt(sec), SKIP_WRITE_BARRIER);
 }
 
 } }  // namespace v8::internal