[modules] Implement @@iterator on namespace objects.

src/ast/ast-types.cc

Index: src/ast/ast-types.cc
diff --git a/src/ast/ast-types.cc b/src/ast/ast-types.cc
index 3c130d8e75d22b38570b3cffdcc565d78e6bb363..edbeef7cc551b738c3de2dc21edabd64a8230962 100644
--- a/src/ast/ast-types.cc
+++ b/src/ast/ast-types.cc
@@ -209,6 +209,7 @@ AstType::bitset AstBitsetType::Lub(i::Map* map) {
     case JS_CONTEXT_EXTENSION_OBJECT_TYPE:
     case JS_GENERATOR_OBJECT_TYPE:
     case JS_MODULE_NAMESPACE_TYPE:
+    case JS_FIXED_ARRAY_ITERATOR_TYPE:
     case JS_ARRAY_BUFFER_TYPE:
     case JS_ARRAY_TYPE:
     case JS_REGEXP_TYPE:  // TODO(rossberg): there should be a RegExp type.