Send HMR updates only for files on the bundle

Summary:
public

Compute the dependencies of the bundle entry file just before sending HMR updates. In case the file that was changed doesn't belong to the bundle bail.

Reviewed By: vjeux

Differential Revision: D2793736

fb-gh-sync-id: f858e71b0dd5fe4f5b2307a22c6cef627eb66a22

packager/react-packager/src/Resolver/index.js

@@ -99,6 +99,10 @@ class Resolver {
     this._polyfillModuleNames = opts.polyfillModuleNames || [];
   }
 
+  getShallowDependencies(entryFile) {
+    return this._depGraph.getShallowDependencies(entryFile);
+  }
+
   getDependencies(main, options) {
     const opts = getDependenciesValidateOpts(options);