Building blocks for sync splitting

Reviewed By: jeanlauliac

Differential Revision: D8380215

fbshipit-source-id: 0aa9a7be82fced6e60c09f842f31f9eac14f1db0

Author: Simon Posada Fishman

packages/metro/src/ModuleGraph/types.flow.js

@@ -47,8 +47,8 @@ type GraphOptions = {|
 |};
 
 export type GraphResult = {|
-  entryModules: $ReadOnlyArray<Module>,
-  modules: $ReadOnlyArray<Module>,
+  entryModules: Array<Module>,
+  modules: Array<Module>,
 |};
 
 export type ModuleIds = {|