Fix comments, including duplicate is, wrong phrases and articles, misspellings, etc.
Change-Id: I8bfea53b9b275e649757cc4bee6a8a026ed9c7a4
Reviewed-on: https://go-review.googlesource.com/c/go/+/493035 Reviewed-by: Benny Siegert <bsiegert@gmail.com> Reviewed-by: Ian Lance Taylor <iant@google.com>
Run-TryBot: shuang cui <imcusg@gmail.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Ian Lance Taylor <iant@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>