first, remove this line:
second, there is likely some confusion around the naming here which we need to address. The TestRunnerBase is a left over name from FlexUnit1 that we should really change. It is just a UI at this point, it doesn't actually have anything to do with running tests. But your code looks a bit like a combination of FlexUnit .9 and FlexUnit 4, so be careful there. I would really recommend grabbing the FlexUnit4 turnkey project and ensuring you are using all of the libraries from there:
Below is an example of the corrected syntax from the FlexUnit 4 turnkey project. You will not a few difference, first, there is no call to runRunner, the UI listens to the FlexUnitCore which does all of the running. Also, to reinforce this the TestRunnerBase is named UIListener (which was my first clue that there were somethings copied from a FlexUnit1 project). You can dowload the turnkey project completely from opensource.adobe.com
core = new FlexUnitCore();
core.addListener( new UIListener( uiListener ));
core.run( whatever you want );
width="100%" height="100%" />
thx, I took the swc from the zip and not the one build from flex3 and took the example and it works.
Keep up the good work !