Presumably each line in the descriptor should match the corresponding operation.

Change-Id: I7726befcd62147324764d15c26e737357122be51
GitHub-Last-Rev: 85e610e3045950b8688a7a506b37a2a92ac7445c
GitHub-Pull-Request: golang/go#24807
Reviewed-on: https://go-review.googlesource.com/106355Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>