Various CastingPerf benchmarks regressed in RC1, e.g.  Namely: - [ObjFooIsObj2](https://pvscmdupload.blob.core.windows.net/reports/allTestHistory%2frefs%2fheads%2fmain_x64_ubuntu%2018.04%2fPerfLabTests.CastingPerf.ObjFooIsObj2.html) - [ObjFooIsObj](https://pvscmdupload.blob.core.windows.net/reports/allTestHistory%2frefs%2fheads%2fmain_x64_ubuntu%2018.04%2fPerfLabTests.CastingPerf.ObjFooIsObj.html) - [IntObj](https://pvscmdupload.blob.core.windows.net/reports/allTestHistory%2frefs%2fheads%2fmain_x64_ubuntu%2018.04%2fPerfLabTests.CastingPerf.IntObj.html) - [IFooFooIsIFoo](https://pvscmdupload.blob.core.windows.net/reports/allTestHistory%2frefs%2fheads%2fmain_x64_ubuntu%2018.04%2fPerfLabTests.CastingPerf.IFooFooIsIFoo.html) - [FooObjIsNull](https://pvscmdupload.blob.core.windows.net/reports/allTestHistory%2frefs%2fheads%2fmain_x64_ubuntu%2018.04%2fPerfLabTests.CastingPerf.FooObjIsNull.html) - [FooObjIsFoo2](https://pvscmdupload.blob.core.windows.net/reports/allTestHistory%2frefs%2fheads%2fmain_x64_ubuntu%2018.04%2fPerfLabTests.CastingPerf.FooObjIsFoo2.html) - [FooObjIsFoo](https://pvscmdupload.blob.core.windows.net/reports/allTestHistory%2frefs%2fheads%2fmain_x64_ubuntu%2018.04%2fPerfLabTests.CastingPerf.FooObjIsFoo.html) - [FooObjCastIfIsa](https://pvscmdupload.blob.core.windows.net/reports/allTestHistory%2frefs%2fheads%2fmain_x64_ubuntu%2018.04%2fPerfLabTests.CastingPerf.FooObjCastIfIsa.html) Commit range: https://github.com/dotnet/runtime/compare/f58a7902a0b4fc9914494de820a7aae8045abd48...01e2521dcee2a05791228decd2951eee1b9eb757