agnivade and bradfitz godoc,blog: perform minor cleanup
- Remove a stray comment which was no longer needed. The accompanying
issue golang.org/issue/7524 was discussed and closed.
- Combine 2 if conditions into a single if-else because
length of a slice can never be negative.
- Remove http links from golangOrgAbsLinkReplacer now that all
links have been changed to https in the blog articles.

Change-Id: I2fe2ec245b580a91760c9331e9626b367f1b6740
Reviewed-on: https://go-review.googlesource.com/107155
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Latest commit 327197e Apr 3, 2018