[aarch64-port-dev ] RFR (XS) 8252366: Shenandoah: revert/cleanup changes in graphKit.cpp

[Roland Westrelin]

> This is aarch64-port/jdk8u-shenandoah specific issue:
>    https://bugs.openjdk.java.net/browse/JDK-8252366
>
> The assert seems to fail on ppc64. Also, we might inline g1_write_barrier_pre_helper for clarity.
>
> 8u webrev:
>    https://cr.openjdk.java.net/~shade/8252366/webrev.01/

I don't see where on this code path a load barrier would be added. Am I
missing something?

Roland.