wait for kernel_ready after ws_closed_error

IPython/html/tests/services/kernel.js

@@ -269,6 +269,8 b' casper.notebook_test(function () {'
             });
         }
     );
+    // wait for any last idle/busy messages to be handled
+    this.wait_for_kernel_ready();
 
     // start the kernel back up
     this.thenEvaluate(function () {