Simplify web platform test runner
Simplify web platform test runner

No longer listens for a specific line of output to determine whether the server is up, which was error-prone (https://github.com/w3c/web-platform-tests/issues/2260). Instead just polls waiting for the server to come up.

fiftin/jsdom,Joris-van-der-Wel/jsdom,Joris-van-der-Wel/jsdom,nicolashenry/jsdom,Sebmaster/jsdom,mbostock/jsdom,mbostock/jsdom,fiftin/jsdom,mzgol/jsdom,nicolashenry/jsdom,mbostock/jsdom,Joris-van-der-Wel/jsdom,snuggs/jsdom,fiftin/jsdom,mzgol/jsdom,Zirro/jsdom,mzgol/jsdom,Sebmaster/jsdom,nicolashenry/jsdom,snuggs/jsdom,tmpvar/jsdom,Sebmaster/jsdom,Zirro/jsdom,tmpvar/jsdom