jQuery 3.0 & 3.1 used `getBoundingClientRect()` in its `width`/`height`
calculations and that causes minor differences in fractional width computations.
Allow a tiny delta in tests to fix those tests breaking in Firefox.
Ref jquery/jquery#3561
Closes gh-2159
This helps fix issues that make tooltip tests sometimes fail when run against
jQuery 3.2 or newer due to timing differences.
Details:
* Add the `moduleAfterEach` function ensuring no timers are running.
* Attach this function via `common.testWidget`.
* Attach this function to most test suites.
* Add a tooltip test helper cleaning up leftover timers.
* Rename legacy `setup`/`teardown` hooks to `beforeEach`/`afterEach`.
Closes gh-1920
