processedAddonJsFiles(inputTree) {
    let preprocessedAddonJS = this._addonPreprocessTree('js', inputTree);

    let processedAddonJS = this.preprocessJs(preprocessedAddonJS, '/', this.name, {
      annotation: `processedAddonJsFiles(${this.name})`,
      registry: this.registry,
      treeType: 'addon',
    });

    if (registryHasPreprocessor(this.registry, 'js')) {
      return this._addonPostprocessTree('js', processedAddonJS);
    }

    throw new SilentError(
      `Addon files were detected in \`${this._treePathFor('addon')}\`, but no JavaScript ` +
        `preprocessor was found for \`${this.name}\`. Please make sure to add a preprocessor ` +
        '(most likely `ember-cli-babel`) to `dependencies` (NOT `devDependencies`) in ' +
        `\`${this.name}\`'s \`package.json\`.`
    );
  }
Returns a tree with all javascript for this addon.

    @private
    @method processedAddonJsFiles
    @param {Tree} the tree to preprocess
    @return {Tree} Processed javascript file tree