Service Worker: Add initialization step for getRegistrations.html layout test.

LayoutTests/http/tests/serviceworker/multiple-register.html

Index: LayoutTests/http/tests/serviceworker/multiple-register.html
diff --git a/LayoutTests/http/tests/serviceworker/multiple-register.html b/LayoutTests/http/tests/serviceworker/multiple-register.html
index 64b307ea14bf38234372c63085ac08b4aef6b151..aa213a104270ae75fe610eab19b8fa278e5c8c9e 100644
--- a/LayoutTests/http/tests/serviceworker/multiple-register.html
+++ b/LayoutTests/http/tests/serviceworker/multiple-register.html
@@ -104,7 +104,7 @@ async_test(function(t) {
         registrations.forEach(function(registration) {
             assert_equals(registration, registrations[0],
                           'register should resolve to the same registration');
-        });
+          });
         return registrations[0].unregister();
       })
     .then(function() { t.done(); })