[autotests] tst_qquicktextinput fails too often in CI

The tst_qquicktextinput autotest has failed 11 times in CI between 2013-01-18 and 2013-02-25, and ranks as one of the top most failing test in that time frame. It seems likely that the test needs fixing.

Example of failure: http://lists.qt-project.org/pipermail/ci-reports/2013-January/003725.html