Sauce Labs Are Flaky

[vsavkin]

The Sauce Labs service has always been a bit flaky. But since now we are trying to run our tests not just in Chrome, but also in Safari, IE, and Firefox, the issue has become more serious -- almost every single test run fails.

Example:
https://travis-ci.org/angular/angular.dart/jobs/35452111

[chirayuk]

cc: @chirayuk

[vicb]

+1 to fix the "big flaky"

[vsavkin]

@vicb fixed the typo :)

[vicb]

I liked the previous version better :)

TODO: re-enable Safari tests once this gets fixed