[macosx] Accelerator doesn't work in application without windows

Run the attached test on OS X with jdk9 b124 or later. It fails: its JMenuItem apparently is not activated.

Specifics of the test is, it does not create any windows, no JFrame etc. It also doesn't set explicitly apple.laf.useScreenMenuBar property. Instead, it depends on the new java.awt.Desktop functionality: an application may very well have no window but still use an OS X system menu bar and be useful.

It worked since introducing new Desktop feature until jdk9 b124 -- so we should treat it as a regression in jdk9 timeframe.