hg: jdk9/dev/langtools: 8173893: JShell: reduce memory leaks

[robert.field at oracle.com]

Changeset: e8d71e4be697
Author:    rfield
Date:      2017-02-08 09:12 -0800
URL:       http://hg.openjdk.java.net/jdk9/dev/langtools/rev/e8d71e4be697

8173893: JShell: reduce memory leaks
Reviewed-by: jlahoda

! src/jdk.jshell/share/classes/jdk/internal/jshell/debug/InternalDebugControl.java
! src/jdk.jshell/share/classes/jdk/internal/jshell/tool/JShellTool.java
! src/jdk.jshell/share/classes/jdk/jshell/JShell.java