RenderPerfTest incorrectly measures performance

The test (test/jdk/performance/client/RenderPerfTest) has some flaws in detection of the marker frames and uses Swing timer to periodically check the color of the marker. The timer is not reliable because it could swallow some updates if there are unprocessed ones on the EDT. Also, there is no protection from missing frames, so the test could hang till the end timeout if some updates were not rendered.