Add basic API support for Map & Set

src/factory.h

Index: src/factory.h
diff --git a/src/factory.h b/src/factory.h
index 8eaa216ee84646ba9f3d0d42c8c6d2188be5d69f..7db781e76786a65e62ce27a93cfd2a736603509f 100644
--- a/src/factory.h
+++ b/src/factory.h
@@ -463,6 +463,9 @@ class Factory final {
   Handle<JSDataView> NewJSDataView(Handle<JSArrayBuffer> buffer,
                                    size_t byte_offset, size_t byte_length);
 
+  Handle<JSMap> NewJSMap();
+  Handle<JSSet> NewJSSet();
+
   // TODO(aandrey): Maybe these should take table, index and kind arguments.
   Handle<JSMapIterator> NewJSMapIterator();
   Handle<JSSetIterator> NewJSSetIterator();