With RT-20784 we no longer need to use the javafx.macosx.embedded system property on the Mac since Glass is able to detect the embedded mode automatically. Glass on Gtk still uses this property.

It is suggested to:

1. Remove the need for using the property (e.g. by setting the error trap unconditionally, and only not setting it when e.g. glass.noErrorTrap is specified).

2. After the above is implemented, we should eliminate setting the system property from JFXPanel and FXCanvas code.