content/static: fix content/static/static.go
content/static: fix content/static/static.go

content/static/static.go is fixed, which was not up to date as of
CL 275195. This also fixes TestStaticIsUpToDate.

Change-Id: Iaaaaa056fcc5195dfa2327eec557bde5d66f97ba
Reviewed-on: https://go-review.googlesource.com/c/website/+/275875
Trust: Julie Qiu <8d32267b6b4884cf35adeaccde2b6857ae11aace@golang.org>
Reviewed-by: Bryan C. Mills <1c8aad60184261ccede67f5c63a0d2a3bf3c9ff4@google.com>

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