Parsing of basic module declarations (no imports/exports yet).

src/heap.cc

Index: src/heap.cc
diff --git a/src/heap.cc b/src/heap.cc
index cd8a03e3a6ddf90af03129d78a17e060f6385927..360e98de4994d04cca4d7b801ec14107a043c7cc 100644
--- a/src/heap.cc
+++ b/src/heap.cc
@@ -2221,6 +2221,12 @@ bool Heap::CreateInitialMaps() {
         AllocateMap(FIXED_ARRAY_TYPE, kVariableSizeSentinel);
     if (!maybe_obj->ToObject(&obj)) return false;
   }
+  set_module_context_map(Map::cast(obj));
+
+  { MaybeObject* maybe_obj =
+        AllocateMap(FIXED_ARRAY_TYPE, kVariableSizeSentinel);
+    if (!maybe_obj->ToObject(&obj)) return false;
+  }
   Map* global_context_map = Map::cast(obj);
   global_context_map->set_visitor_id(StaticVisitorBase::kVisitGlobalContext);
   set_global_context_map(global_context_map);