bytes: remove redundant type conversion
bytes: remove redundant type conversion

Change-Id: Icafb2d9fd11b23d3acaf9df07e7f90d8bcd829fa
GitHub-Last-Rev: 2b766460554860510f3fec03a4b9fe2e65fad268
GitHub-Pull-Request: golang/go#49243
Reviewed-on: https://go-review.googlesource.com/c/go/+/360096
Reviewed-by: Brad Fitzpatrick <ae9783c0b0efc69cd85ab025ddd17aa44cdc4aa5@golang.org>
Trust: Brad Fitzpatrick <ae9783c0b0efc69cd85ab025ddd17aa44cdc4aa5@golang.org>
Trust: Martin Möhrmann <54669547a225ff20cba8b75a4adca540eef25858@golang.org>

cloudflare/go,CAFxX/go,nawawi/go,nawawi/go,golang/go,nawawi/go,cloudflare/go,CAFxX/go,nawawi/go,golang/go,golang/go,golang/go,CAFxX/go,nawawi/go,CAFxX/go,cloudflare/go,CAFxX/go,cloudflare/go,golang/go,cloudflare/go,cloudflare/go,nawawi/go,nawawi/go,CAFxX/go,CAFxX/go,cloudflare/go,golang/go,golang/go,nawawi/go,golang/go,CAFxX/go,cloudflare/go