hg: jdk9/sandbox/jdk: 6791812: (file spec) Incompatible File.lastModified() and setLastModified() for negative time

[chris.hegarty at oracle.com]

Changeset: 59902f12fb70
Author:    bpb
Date:      2017-06-13 13:43 -0700
URL:       http://hg.openjdk.java.net/jdk9/sandbox/jdk/rev/59902f12fb70

6791812: (file spec) Incompatible File.lastModified() and setLastModified() for negative time
Summary: Amend verbiage describing return value to explain negative values.
Reviewed-by: rriggs, smarks

! src/java.base/share/classes/java/io/File.java