[gardening] Add some nops into test function.
[gardening] Add some nops into test function.

Right now the vm/cc/CodeRelocator_* tests are written in a strange way
to work around the conservative assumptions the relocator makes.

A future CL will make the relocator insert tramppolines precisely when
they are needed (not conservatively), which will allow writing precise
tests.

TEST=Fixes ARM64 vm/cc/CodeRelocator_* tests

Change-Id: I68f9bcce29f42a2264608f867f177e8f557804fb
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/196666
Reviewed-by: Martin Kustermann <a35dd5b79fac84b2bb3b026a16b8becc55af5961@google.com>
Commit-Queue: Martin Kustermann <a35dd5b79fac84b2bb3b026a16b8becc55af5961@google.com>

dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk