net/http: fix cookie value of "" being interpreted as empty string.
In issue #46443, we have established that double-quotes in cookie values
should be kept as part of the value, rather than being discarded.
However, we have missed the edge case of "" until now. This CL fixes
said edge case.
Fixes #75244
Change-Id: I627ad2376931514aa5dcc8961ad804e42b7d9434
Reviewed-on: https://go-review.googlesource.com/c/go/+/700755 Reviewed-by: Nicholas Husin <husin@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Auto-Submit: Nicholas Husin <husin@google.com> Reviewed-by: Damien Neil <dneil@google.com>