Random coverage

Random timeouts

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ERROR: test_pause_continue (Orange.widgets.visualize.tests.test_owmosaic.MosaicVizRankTests)
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Traceback (most recent call last):
  File "C:\projects\orange3-75xll\build\.test\lib\site-packages\Orange\widgets\visualize\tests\test_owmosaic.py", line 256, in test_pause_continue
    self.process_events(until=lambda: self.vizrank.saved_progress > 20)
  File "C:\projects\orange3-75xll\build\.test\lib\site-packages\Orange\widgets\tests\base.py", line 194, in process_events
    raise TimeoutError()
TimeoutError
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+2 for the above

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ERROR: test_base (Orange.widgets.utils.tests.test_webview.WebviewWidgetTest)
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Traceback (most recent call last):
  File "/home/travis/build/biolab/orange3/build/travis-test/Orange/widgets/utils/tests/test_webview.py", line 22, in test_base
    svg = self.process_events(lambda: w.svg())
  File "/home/travis/build/biolab/orange3/build/travis-test/Orange/widgets/tests/base.py", line 196, in process_events
    raise TimeoutError()
TimeoutError