Failures on Revert "[vm] Migrate FFI callbacks to the new metadata system."...[ddc] Fix for record types with new type system

[aam]

There are new test failures on Revert "[vm] Migrate FFI callbacks to the new metadata system."...[ddc] Fix for record types with new type system.

The tests

ffi/vmspecific_function_callbacks_exit_test/03/0 Fail (expected Pass)
ffi/vmspecific_function_callbacks_exit_test/03/1 Fail (expected Pass)

are failing on configurations

vm-aot-linux-release-arm-qemu
vm-aot-linux-release-riscv64-qemu
vm-aot-linux-release-x64
vm-aot-obfuscate-linux-release-x64
vm-eager-optimization-linux-release-ia32
vm-eager-optimization-linux-release-x64
vm-linux-debug-x64
vm-linux-release-arm-qemu
vm-linux-release-arm64
vm-linux-release-riscv64-qemu
vm-linux-release-x64
vm-reload-linux-release-x64
vm-reload-rollback-linux-release-x64

[liamappelbe]

This test was failing before my original CL, then my CL caused it to start passing, and now the rollback has caused it to fail again: https://dart-ci.firebaseapp.com/#showLatestFailures=false&test=ffi/vmspecific_function_callbacks_exit_test/03/1&configurations=vm-linux-debug-x64

I'm going to reland this CL soonish, so the tests should start passing again.