fix: allow JS test to run after shutdown test

shutdown notebook test closes casper browser, here we re-instatiate it
after the test

IPython/html/tests/casperjs/test_cases/shutdown_notebook.js

@@ -1,31 +1,33 b''
 //
 // Test shutdown of a kernel.
 //
 casper.notebook_test(function () {
     // XXX: test.begin allows named sections but requires casperjs 1.1.0-DEV.
     //      We will put it back into place when the next version of casper is
     //      released. Following that, all instances of this.test can be changed
     //      to just test.
     //this.test.begin("shutdown tests (notebook)", 2, function(test) {
 
     this.thenEvaluate(function () {
         $('#kill_and_exit').click();
     });
     
     this.thenEvaluate(function () {
         var cell = IPython.notebook.get_cell(0);
         cell.set_text('a=10; print(a)');
         cell.execute();
     });
 
     // refactor this into  just a get_output(0)
     this.then(function () {
         var result = this.get_output_cell(0);
         this.test.assertFalsy(result, "after shutdown: no execution results");
         this.test.assertNot(this.kernel_running(), 
             'after shutdown: IPython.notebook.kernel.running is false ');
     });
 
+    this.thenOpen(this.get_notebook_server());
+
 //}); // end of test.begin
 });