Reland and fix "Fix LoadFieldByIndex to take mutable heap-numbers into account.""

src/handles.cc

Index: src/handles.cc
diff --git a/src/handles.cc b/src/handles.cc
index ea0f8aebafa612a348037ebcbaeb1b9710f8d0c8..edb657c53dc95bf61544acb3275266480d55976c 100644
--- a/src/handles.cc
+++ b/src/handles.cc
@@ -682,6 +682,10 @@ Handle<FixedArray> GetEnumPropertyKeys(Handle<JSObject> object,
             if (field_index >= map->inobject_properties()) {
               field_index = -(field_index - map->inobject_properties() + 1);
             }
+            field_index = field_index << 1;
+            if (details.representation().IsDouble()) {
+              field_index |= 1;
+            }
             indices->set(index, Smi::FromInt(field_index));
           }
         }