It turns out it is not legal to pass the results of OpAccessChain as a
function argument, for... reasons. This CL switches us over to passing
the argument via a temp variable instead.
Bug: skia:11748
Change-Id: Ib5e86c1d000655ebd7bb62ceea6a27b823808645
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/385936
Reviewed-by: John Stiles <johnstiles@google.com>
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>
