code: function reduceManifestBundles(input, manifest) {
    // If manifest doesn't have any bundles, then no reducing to do
    if (!manifest.bundles) {
      return input;
    }
  
    // Merge the bundles together, checking for collisions
    return Object.keys(manifest.bundles).reduce((output, bundle) => {
      Ember.assert(`The bundle "${bundle}" already exists.`, !output.bundles[bundle]);
      output.bundles[bundle] = manifest.bundles[bundle];
      return output;
    }, input);
  }
docs: Merges two manifests' bundles together and returns a new manifest.
  
  @param {AssetManifest} input
  @param {AssetManifest} manifest
  @return {AssetManifest} output