RFR 8002297: sun/net/www/protocol/http/StackTraceTest.java fails intermittently

[Chris Hegarty]

Trivial test issue where the test will fail if run on a machine that has 
a process listening on port 8080 ( test expects this port to refuse the 
connection ). The solution is to simply open and close a listening 
socket and use its ephemeral port. Should be good enough.

http://cr.openjdk.java.net/~chegar/8002297/webrev.00/webrev/
-Chris