test_autoRepeat() fails occasionally

The test has started to fail around 15th of Nov. Last week the test has failed 9 times, and week before that 7 times. It's a flaky test, so it doesn't necessarily make the whole integration to fail.

FAIL!  : tst_controls::Default::Button::test_autoRepeat() property count
   Actual   (): 48
   Expected (): 2

Build logs: http://testresults.qt.io/logs/qt/qtquickcontrols2/3e6b3cd911d807f42ad23c31290e023b67f815cf/WindowsWindows_10x86_64WindowsWindows_10x86_64MSVC2015qtci-windows-10-x86_64-b5ea7bDebugAndRelease_Release_OpenGLDynamic/874ce150b2316899370bc96249e988d4c63cd548/testrun_1479471265/testlog.txt.gz

http://testresults.qt.io/logs/qt/qtquickcontrols2/196ca83e9d805c755530670005e6462ea8cee15f/LinuxUbuntu_14_04x86_64LinuxUbuntu_14_04x86_64GCCqtci-linux-Ubuntu-14.04-x86_64-3b1600NoWidgets_ForceDebugInfo/009a0032dfab35344ce5c63516ad882cebd02149/testrun_1479274082/testlog.txt.gz

http://testresults.qt.io/logs/qt/qtquickcontrols2/f09f119363d9174c884400dfccdc34ced5627859/WindowsWindows_10x86WindowsWindows_10x86MSVC2015qtci-windows-10-x86-5c95a9DebugAndRelease_Release_OpenGLDynamic/05f104a9334998264bfb87ca89021c9511bffe66/testrun_web_qt_qt5_1479405162187/testlog.txt.gz