hg: amber/amber: improving error message for leaves in a sealed hierarchy

[vicente.romero at oracle.com]

Changeset: dbb5d90508b2
Author:    vromero
Date:      2019-09-25 13:32 -0400
URL:       https://hg.openjdk.java.net/amber/amber/rev/dbb5d90508b2

improving error message for leaves in a sealed hierarchy

! src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Enter.java
! src/jdk.compiler/share/classes/com/sun/tools/javac/resources/compiler.properties