HMR: Include updated modules in the correct order

Reviewed By: davidaurelio

Differential Revision: D5852269

fbshipit-source-id: 519564a4899b22d16a2ab3be4b466e21783e8f86

packages/metro-bundler/src/HmrServer/index.js

@@ -129,7 +129,10 @@ class HmrServer<TClient: Client> {
       // The Delta Bundle can have null objects: these correspond to deleted
       // modules, which we don't need to send to the client.
       if (module != null) {
-        modules.push({id, code: module.code});
+        // When there are new modules added on the dependency tree, they are
+        // appended on the Delta Bundle, but HMR needs to have them at the
+        // beginning.
+        modules.unshift({id, code: module.code});
       }
     }