Check for stringer on the key itself.
This is useful for locally defined context key types,
where there may be multiple instances of that type.
For example, see http.contextKey,
which can now be called after this change.
For the value itself, print the type at least
instead of just resorting to "<not stringer>".
Change-Id: I588ef1df34e90fb9ebd83cb180fea495e1fedaa8
Reviewed-on: https://go-review.googlesource.com/c/go/+/555697 Reviewed-by: Damien Neil <dneil@google.com> Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Run-TryBot: Joseph Tsai <joetsai@digital-static.net>
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