hg: kulla/dev/langtools: Fix handling of null expression values

[robert.field at oracle.com]

Changeset: b72290ca582c
Author:    rfield
Date:      2014-11-24 15:42 -0800
URL:       http://hg.openjdk.java.net/kulla/dev/langtools/rev/b72290ca582c

Fix handling of null expression values

! repl/src/tool/RuntimeSupport.java
! repl/src/tool/Util.java