Tests: Increase QUnit timeout

Tests: Increase QUnit timeout

Android 2.3 is very slow & times out a lot in async tests, they have to be
restarted multiple times to settle. Long test execution is not a huge problem
as Android 2.3 is tested only periodically during the night, unstable tests
are a bigger problem. This might mitigate that.

In a regular scenario almost all tests should pass so increasing the timeout
for all browsers shouldn't have a huge impact on overall test time.

(cherry-picked from ff18d8e2060ae7c15c7694dc6bcbbeb9cbfbdaa4)

Closes gh-2232