All we care about w.r.t FieldType is object identity. Moreover,
FieldType does not have its own instance type. Hence it makes no
sense to have the broker know about FieldType at all.

Bug: v8:7790
Change-Id: I585e7e06826fae95890c1889ae2f4613479cbb32
Reviewed-on: https://chromium-review.googlesource.com/1151300
Commit-Queue: Georg Neis <neis@chromium.org>
Reviewed-by: Sigurd Schneider <sigurds@chromium.org>
Cr-Commit-Position: refs/heads/master@{#54725}