Track representations of fields

src/bootstrapper.cc

Index: src/bootstrapper.cc
diff --git a/src/bootstrapper.cc b/src/bootstrapper.cc
index 12f0cdac6b7faef80bc5f2d8299560696f315a47..f86baa6c92683a32cc1de8f1a952e28dc3086a2e 100644
--- a/src/bootstrapper.cc
+++ b/src/bootstrapper.cc
@@ -1000,6 +1000,7 @@ bool Genesis::InitializeGlobal(Handle<GlobalObject> inner_global,
       FieldDescriptor field(heap->last_index_string(),
                             JSRegExp::kLastIndexFieldIndex,
                             writable);
+      field.SetStorageType(TAGGED);
       initial_map->AppendDescriptor(&field, witness);
     }
 
@@ -1152,6 +1153,7 @@ bool Genesis::InitializeGlobal(Handle<GlobalObject> inner_global,
 
     {  // length
       FieldDescriptor d(*factory->length_string(), 0, DONT_ENUM);
+      d.SetStorageType(TAGGED);
       map->AppendDescriptor(&d, witness);
     }
     {  // callee
@@ -1918,6 +1920,7 @@ bool Genesis::InstallNatives() {
       FieldDescriptor index_field(heap()->index_string(),
                                   JSRegExpResult::kIndexIndex,
                                   NONE);
+      index_field.SetStorageType(TAGGED);
       initial_map->AppendDescriptor(&index_field, witness);
     }