Keep unit test results data under 64 KB

When our unit test results data is larger than 64 KB, Saucelabs ignores it.
This is causing missing entries in our unit test results table. Our
callstacks can be quite large so the fix is to omit all but the first few
callstacks from the unit test results data.
Make TooltipHidingTests more robust. #127

The TooltipHidingTests are currently flaky. The cause seems to be that the
timeframe in which the tooltip is expected to dismiss is too small. The
tooltip is behaving correctly as long as it dismisses faster than
DEFAULT_MESSAGE_DURATION so I extended the expected timeframe while
keeping it under that threshold.