[8u] Review request: Backport various Ensemble8 bug fixes to 8u

[Kevin Rushforth]

Vadim, Chien, and Daniil,

Please review the following to backport several bug fixes in Ensemble8 
from FX 9 to FX 8u:

https://bugs.openjdk.java.net/browse/JDK-8168611

This is an umbrella task that needs a little explanation. We need to 
replace the old Ensemble2 demo on OTN with Ensemble8 (see JDK-8160020 
[1] for why this is the case). We further need to compile Ensemble8 with 
JDK 8u so that it will run on both JDK 8u and JDK 9. In support of this, 
I propose to backport 12 bugs from FX 9 to FX 8u-dev -- as 12 separate 
changesets, one for each bug -- so the version we deploy on OTN will 
have all of the needed bug fixes and run correctly on both JDK 8u and JDK 9.

Further details are in the umbrella bug report.

-- Kevin

[1] https://bugs.openjdk.java.net/browse/JDK-8160020