Move cacheinvalidation testing file to a testing build target

This allows third_party/cache_invalidation to be checked
with gn check (as soon as it's enabled in //.gn).

Bug: 898837
Change-Id: Ica669d8a7277178878d630b54879e1439350f566
Reviewed-on: https://chromium-review.googlesource.com/c/1307496
Reviewed-by: Nicolas Zea <zea@chromium.org>
Commit-Queue: Daniel Bratell <bratell@opera.com>
Cr-Commit-Position: refs/heads/master@{#604196}
1 file changed