Make sure builtins preserve guarantees about empty element array prototypes.

src/objects.cc

Index: src/objects.cc
diff --git a/src/objects.cc b/src/objects.cc
index 037d33c5039daeec1dac8458ad459d8ddf93985c..18387ea8eec64e3bf8b9efa5557e7cd2f622d073 100644
--- a/src/objects.cc
+++ b/src/objects.cc
@@ -12745,6 +12745,7 @@ MaybeHandle<Object> JSObject::SetFastElement(Handle<JSObject> object,
   // make sure all of these optimizations are invalidated.
   if (isolate->is_initial_object_prototype(*object) ||
       isolate->is_initial_array_prototype(*object)) {
+    PrintF("Deopting\n");

[Jakob Kummerow, 2015/04/20 10:52:05]

debugging leftover?

[mvstanton, 2015/04/20 14:10:39]

Done.

     object->map()->dependent_code()->DeoptimizeDependentCodeGroup(isolate,
         DependentCode::kElementsCantBeAddedGroup);
   }