improve abstract property support (closes #11610)

Thanks to Darren Dale for patch.
diff --git a/Misc/ACKS b/Misc/ACKS
index c74b811..e47d738 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -220,6 +220,7 @@
 Antonio Cuni
 Brian Curtin
 Lisandro Dalcin
+Darren Dale
 Andrew Dalke
 Lars Damerow
 Evan Dandrea