[unified-heap] Remove wrong collections test

Removes a test that was checking that a JS wrapper was collected when
doing a V8 GC. This relies on the fact that wrapper tracing does not
see the back references in LiveNodeList::owner_.

No-try: true
Bug: 843903
Change-Id: I0586ba63f15d686a6e33c152d9eb9a8f08247cd5
Reviewed-on: https://chromium-review.googlesource.com/1243066
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#593979}
2 files changed