Even though the WorkInProgress design proposal only mentions that WIP
changes are subtracted from "Incoming reviews" section:
"
The query driving the existing *Incoming reviews* section subtracts WIP
changes from the result. This has the effect of hiding WIP changes from
their reviewers' dashboards.
"
consistently also subtract the WIP changes from the "CCed on" dashboard
section.
Bug: Issue 12850
Change-Id: Ibab954bb6b3b8a66d4da842bc1ac3f53e8e18a68