We are exploring making this easier, by enabling a developer to build a set of javafx.* modules that can be used with a clean OpenJDK build (without the javafx.* modules). Stay tuned.
Building WebKit as part of building JavaFX is optional and requires additional steps; these are detailed per operating system below. If you do not build WebKit, you can use pre-built libraries as detailed here.
You will need Windows 7 or later (Windows 10 is recommended) 64-bit OS