hg: amber/amber: sync-ing the implementation with current spec

[vicente.romero at oracle.com]

Changeset: a81e34480b9f
Author:    vromero
Date:      2020-02-11 20:42 -0500
URL:       https://hg.openjdk.java.net/amber/amber/rev/a81e34480b9f

sync-ing the implementation with current spec

! src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Attr.java
! src/jdk.compiler/share/classes/com/sun/tools/javac/resources/compiler.properties
! test/langtools/tools/javac/sealed/SealedCompilationTests.java
! test/langtools/tools/javac/sealed/SealedDiffConfigurationsTest.java