hg: openjfx/8u-dev/rt: 8215685: Change JavaFX release version to 8u999

[kevin.rushforth at oracle.com]

Changeset: 9a8654110621
Author:    kcr
Date:      2019-01-08 14:22 -0800
URL:       http://hg.openjdk.java.net/openjfx/8u-dev/rt/rev/9a8654110621

8215685: Change JavaFX release version to 8u999
Reviewed-by: prr

! build.properties