The testcase in the URL causes run-webkit-tests to hang when trying to process that file for pixel tests. It seems it is hanging on all test cases that use the Infinity keyword. It seems that DumpRenderTree Qt is reporting an incorrect PNG length when dumping the PNG data (or more likely that the PNG data is being truncated), which is causing run-webkit-tests to hang waiting for more data which doesn't come.
The URL is not valid. Please attach the testcase to this bug.