HEADS-UP: switching to JDK 9 as boot JDK

[Kevin Rushforth]

As I mentioned during the review of JDK-8134709, we are working toward 
upgrading the boot JDK for FX to JDK 9. Our target is to do this after 
JDK 9 build 109 is promoted near the end of next week. As part of this, 
we will be moving to gradle 2.11 since version 2.9 does not support JDK 
9. Developers are encouraged to get gradle 2.11 some time before then.

I will send out more details about the switch later this week or early next.

-- Kevin