diff --git a/testing/web-platform/tests/html/infrastructure/urls/resolving-urls/query-encoding/resources/resolve-url.js b/testing/web-platform/tests/html/infrastructure/urls/resolving-urls/query-encoding/resources/resolve-url.js
index 000b9020df9d8..caf1deba510e6 100644
--- a/testing/web-platform/tests/html/infrastructure/urls/resolving-urls/query-encoding/resources/resolve-url.js
+++ b/testing/web-platform/tests/html/infrastructure/urls/resolving-urls/query-encoding/resources/resolve-url.js
@@ -274,6 +274,142 @@ got
 ;
 }
 function
+poll_for_stash
+(
+test_obj
+uuid
+expected
+)
+{
+var
+start
+=
+new
+Date
+(
+)
+;
+var
+poll
+=
+test_obj
+.
+step_func
+(
+function
+(
+)
+{
+var
+xhr
+=
+new
+XMLHttpRequest
+(
+)
+;
+xhr
+.
+open
+(
+'
+GET
+'
+stash_take
++
+uuid
+)
+;
+xhr
+.
+onload
+=
+test_obj
+.
+step_func
+(
+function
+(
+e
+)
+{
+if
+(
+xhr
+.
+response
+=
+=
+"
+"
+)
+{
+if
+(
+new
+Date
+(
+)
+-
+start
+>
+10000
+)
+{
+test_obj
+.
+force_timeout
+(
+)
+;
+}
+test_obj
+.
+step_timeout
+(
+poll
+200
+)
+;
+}
+else
+{
+assert_equals
+(
+xhr
+.
+response
+expected
+)
+;
+test_obj
+.
+done
+(
+)
+;
+}
+}
+)
+;
+xhr
+.
+send
+(
+)
+;
+}
+)
+test_obj
+.
+step_timeout
+(
+poll
+200
+)
+;
+}
+function
 test_load_nested_browsing_context
 (
 tag