LayoutIteration is missing null markers. Added the test from tobias to SubstitutabilityTest.
------------- Commit messages: - 8372729 Changes: https://git.openjdk.org/valhalla/pull/1790/files Webrev: https://webrevs.openjdk.org/?repo=valhalla&pr=1790&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8372729 Stats: 63 lines in 2 files changed: 63 ins; 0 del; 0 mod Patch: https://git.openjdk.org/valhalla/pull/1790.diff Fetch: git fetch https://git.openjdk.org/valhalla.git pull/1790/head:pull/1790 PR: https://git.openjdk.org/valhalla/pull/1790
