test: remove unused variables form http tests

The http tests seem especially prone to including unused variables.
This change removes them.

PR-URL: https://github.com/nodejs/node/pull/4422
Reviewed-By: Johan Bergström <bugs@bergstroem.nu>

test/parallel/test-http-url.parse-https.request.js

@@ -10,7 +10,6 @@ var https = require('https');
 
 var url = require('url');
 var fs = require('fs');
-var clientRequest;
 
 // https options
 var httpsOptions = {