hg: amber/amber/langtools: before reflectively accessing a potential field it must be checked that it is actually a field

[vicente.romero at oracle.com]

Changeset: 85ba48698ef6
Author:    vromero
Date:      2017-09-22 11:28 -0400
URL:       http://hg.openjdk.java.net/amber/amber/langtools/rev/85ba48698ef6

before reflectively accessing a potential field it must be checked that it is actually a field

! src/jdk.compiler/share/classes/com/sun/tools/javac/comp/ConstablesVisitor.java