This task is created to add manual tests to the manual test groups. In addition, fix is provided for TestMatrix.java#Downcall-F and TestMatrix.java#Downcall-T which are failing due to missing TestDowncall.java ([JDK-8287158](https://bugs.openjdk.org/browse/JDK-8287158)).
------------- Commit messages: - Updated Manual Test Groups Changes: https://git.openjdk.org/jdk/pull/10864/files Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=10864&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8295859 Stats: 42 lines in 2 files changed: 35 ins; 0 del; 7 mod Patch: https://git.openjdk.org/jdk/pull/10864.diff Fetch: git fetch https://git.openjdk.org/jdk pull/10864/head:pull/10864 PR: https://git.openjdk.org/jdk/pull/10864
