There is existing build logic in the ":web" project to run the tests in headless mode. This logic was inadvertently commented out during the upgrade to building with a Jigsaw boot JDK as part of JDK-8161704.

This is causing three problems:

1. We are unable to run our smoke tests on Linux without a valid DISPLAY

2. When running our smoke tests on Mac it sometimes can hang if system has no display; also it can steal the focus when running on your desktop.

3. It is causing the newly added unit test for JDK-8162922 to fail on Hi-DPI screens.

The first two problems were the reason we started running the web tests in headless mode in the first place (see JDK-8094088).