hg: jdk10/jdk10/langtools: 8184894: Mark ExternalEditorTest.java as intermittently failing, demote to tier 2

[amy.lu at oracle.com]

Changeset: ec16ccfea03a
Author:    amlu
Date:      2017-07-28 19:54 +0800
URL:       http://hg.openjdk.java.net/jdk10/jdk10/langtools/rev/ec16ccfea03a

8184894: Mark ExternalEditorTest.java as intermittently failing, demote to tier 2
Reviewed-by: jlahoda

! test/TEST.groups
! test/jdk/jshell/ExternalEditorTest.java