function methodsForTreeType(treeType) {
  let treeMethods = DEFAULT_TREE_FOR_METHOD_METHODS[treeType];

  return GLOBAL_TREE_FOR_METHOD_METHODS.concat(treeMethods);
}
Allow addons to implement contentFor method to add string output into the associated `{{content-for 'foo'}}` section in `index.html`
*Uses:**

 - For instance, to inject analytics code into `index.html`

 @public
 @method contentFor
 @param type
 @param config
 @param content

 @example
 - [ember-cli-google-analytics](https://github.com/pgrippi/ember-cli-google-analytics/blob/v1.5.0/index.js#L79)