1bcbcfd56f
This reverts commit d0bc83ca275964fa1de6684c3cdc6714de386efd. Protractor-based prerendering is flakey on Travis and takes several minutes to complete, slowing down the build. Prerendering has a lower impact now that we use a ServiceWorker. We will revisit in the future (probably using a `PlatformServer`-based approach). PR Close #15346