Merge pull request dotnet/coreclr#22656 from briansull/fix_arm64_assert
authorBrian Sullivan <briansul@microsoft.com>
Wed, 20 Feb 2019 01:31:27 +0000 (17:31 -0800)
committerGitHub <noreply@github.com>
Wed, 20 Feb 2019 01:31:27 +0000 (17:31 -0800)
ARM64: Correct the assert to add R8 as a potential valid arg register

Commit migrated from https://github.com/dotnet/coreclr/commit/89c33a222cc5798d02b6d0b7c4b98562da2c212c


Trivial merge