REGRESSION (191898) idbobjectstore-*-failures.html tests fail in Release builds
Before this revision, they were only flaky.
Only realistic explanation for failing in Release and not Debug is timing.
I'm working on bulletproofing the tests against this once and for all
Having trouble building release with my current setup, but these changes I'm about to land work great in Debug, and *should* remove the flakiness in release once and for all.