Revert "Skip unstable test"

This reverts commit 8e0c5b59f57b51a0dc80d3d8274202776c6e03df.

This test doesn't fail any more.

Task-number: QTBUG-23976
Change-Id: I77704e7811c4c335cb5836ba7645a8804c13e12d
Reviewed-by: Gabriel de Dietrich <gabriel.dedietrich@digia.com>