This reverts commit 067bb443af.
Reason for revert:
Failing Darwin-arm builds because that testing environment does not access testdata
from sibling directories. A future change will likely be made to move this testdata
out of src/testdata to create a solution that doesn't require the single-file directory.
Updates #27151
Change-Id: I8dbf5dd9512c94a605ee749ff4655cb00b0de686
Reviewed-on: https://go-review.googlesource.com/138737
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
43cd907017