function register() {
  NodeCollection.register();
  Collection.registerMethods(globalMethods, types.Node);
  Collection.registerMethods(traversalMethods, JSXElement);
}
Given a JSXElement, returns its "root" name. E.g. it would return "Foo" for
both <Foo /> and <Foo.Bar />.

@param {NodePath} path
@return {string}