JBS: possibilty to merge issues?

[Jeanette Winzenburg]

Currently working on two related issues:

https://bugs.openjdk.java.net/browse/JDK-8187309: TreeCell must not  
change data of treeView
https://bugs.openjdk.java.net/browse/JDK-8187473: TreeView must have  
default commit handler

which are so intertwined that there's no way to fix one without the  
other (we must have a default commit mechanism in place at any time).  
I could merge them in the PR (also-fixes), but would feel cleaner to  
merge in JBS, if possible.

-- Jeanette