time: avoid unnecessary type conversions
time: avoid unnecessary type conversions

Change-Id: Ic318c25b21298ec123eb27c814c79f637887713c
Reviewed-on: https://go-review.googlesource.com/97135
Run-TryBot: Kunpei Sakai <16e6eef4865510c955b62d2536a11db5146a1308@gmail.com>
TryBot-Result: Gobot Gobot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>
Reviewed-by: Brad Fitzpatrick <ae9783c0b0efc69cd85ab025ddd17aa44cdc4aa5@golang.org>

akutz/go,akutz/go,CAFxX/go,nawawi/go,Cofyc/go,golang/go,akutz/go,golang/go,nawawi/go,josharian/go,josharian/go,codestation/go,CAFxX/go,Cofyc/go,golang/go,cloudflare/go,akutz/go,nawawi/go,Cofyc/go,akutz/go,CAFxX/go,golang/go,josharian/go,CAFxX/go,CAFxX/go,cloudflare/go,josharian/go,josharian/go,codestation/go,cloudflare/go,cloudflare/go,golang/go,akutz/go,Cofyc/go,Cofyc/go,golang/go,nawawi/go,josharian/go,CAFxX/go,akutz/go,CAFxX/go,akutz/go,nawawi/go,Cofyc/go,Cofyc/go,codestation/go,cloudflare/go,codestation/go,nawawi/go,josharian/go,golang/go,nawawi/go,cloudflare/go,codestation/go,codestation/go,golang/go,codestation/go,cloudflare/go,CAFxX/go,codestation/go,Cofyc/go,cloudflare/go,nawawi/go,josharian/go