go: various minor cleanups with the help of Goland
• fix some typos
• remove superfluous conversions/parentheses
• remove superfluous nil checks
Change-Id: I428bf6a7be551b79270567047878c3076dd6f2ff
GitHub-Last-Rev:
3b1c7573cfdf89ac184fd6ae44bca4be78b0cd64
GitHub-Pull-Request: golang/go#45799
Reviewed-on: https://go-review.googlesource.com/c/go/+/314069
Reviewed-by: Robert Griesemer <gri@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>
Trust: Robert Griesemer <gri@golang.org>
Run-TryBot: Robert Findley <rfindley@google.com>