runtime: correct variable name in comment
runtime: correct variable name in comment

Change-Id: Ic35ec2ed320c3c266afbeec8bdea1dedac4725e4
Reviewed-on: https://go-review.googlesource.com/c/go/+/336892
Reviewed-by: Ian Lance Taylor <87e9c6d529889242b7e184afb632328636553ab4@golang.org>
Trust: Austin Clements <7ea35d812706d9213868749011af1ed4fa2f6aa0@google.com>

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