[unified-heap] Fix test runner

Some tests rely on properly collecting objects on tear down. E.g. mock
objects are expected to die after a test finishes.

Bug: 843903
Change-Id: Ica1daee98be3625e4f2202fe0a73b290b5130ce9
Reviewed-on: https://chromium-review.googlesource.com/c/1293489
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#601544}
1 file changed