Fix Chromium issue 47824.

src/handles.h

Index: src/handles.h
diff --git a/src/handles.h b/src/handles.h
index 96b17a653cf29f8826d2e96bc1c7056d6d801f83..1e14daf9a936e3fd10c17c311eecc052b95ae859 100644
--- a/src/handles.h
+++ b/src/handles.h
@@ -193,8 +193,14 @@ void NormalizeProperties(Handle<JSObject> object,
 void NormalizeElements(Handle<JSObject> object);
 void TransformToFastProperties(Handle<JSObject> object,
                                int unused_property_fields);
+
+// Flattens a string.
 void FlattenString(Handle<String> str);
 
+// Flattens a string and returns the underlying external or sequential
+// string.
+Handle<String> FlattenGetString(Handle<String> str);
+
 Handle<Object> SetProperty(Handle<JSObject> object,
                            Handle<String> key,
                            Handle<Object> value,