Make the Deprecation/Intervention report IDLs match the spec.

See spec here: https://wicg.github.io/reporting/#report-types

Specifically, some fields in the IDLs were originally not
marked nullable, but now are.

Bug: 564071, 731810
Change-Id: I731ee46f39920c864856f7eda7f18045f779d1c3

TBR: rbyers@chromium.org
Change-Id: I731ee46f39920c864856f7eda7f18045f779d1c3
Reviewed-on: https://chromium-review.googlesource.com/1097602
Commit-Queue: Paul Meyer <paulmeyer@chromium.org>
Reviewed-by: Nate Chapin <japhet@chromium.org>
Cr-Commit-Position: refs/heads/master@{#567064}
12 files changed