hg: jdk/jdk13: 8227391: Update double-conversion to version 3.1.5

[hannes.wallnoefer at oracle.com]

Changeset: 70b1c1bec669
Author:    hannesw
Date:      2019-07-11 17:11 +0200
URL:       https://hg.openjdk.java.net/jdk/jdk13/rev/70b1c1bec669

8227391: Update double-conversion to version 3.1.5
Reviewed-by: attila

! src/jdk.scripting.nashorn/share/classes/jdk/nashorn/internal/runtime/doubleconv/Bignum.java
! src/jdk.scripting.nashorn/share/classes/jdk/nashorn/internal/runtime/doubleconv/FixedDtoa.java
! src/jdk.scripting.nashorn/share/classes/jdk/nashorn/internal/runtime/doubleconv/IeeeDouble.java
! test/nashorn/src/jdk/nashorn/internal/runtime/doubleconv/test/BignumDtoaTest.java
! test/nashorn/src/jdk/nashorn/internal/runtime/doubleconv/test/FixedDtoaTest.java
! test/nashorn/src/jdk/nashorn/internal/runtime/doubleconv/test/IeeeDoubleTest.java