git: openjdk/mobile: 8230794: Improve assert to get more information about the JDK-8227695 failure

[duke]

Changeset: a73f96ef
Author:    Thomas Schatzl <tschatzl at openjdk.org>
Date:      2019-09-11 10:19:09 +0000
URL:       https://github.com/openjdk/mobile/commit/a73f96ef

8230794: Improve assert to get more information about the JDK-8227695 failure

Reviewed-by: kbarrett, sjohanss

! src/hotspot/share/gc/g1/g1CollectedHeap.cpp