1 files changed, 19 insertions, 0 deletions
diff --git a/docshell/test/navigation/iframe_slow_onload_inner.html b/docshell/test/navigation/iframe_slow_onload_inner.html
new file mode 100644
index 0000000000..ad39eba795
--- /dev/null
+++ b/docshell/test/navigation/iframe_slow_onload_inner.html
@@ -0,0 +1,19 @@
+<html>
+  <head>
+    <script>
+      function load() {
+        // Let the test page know that it can try to navigate.
+        top.postMessage("onload", "*");
+        // We're starting an infinite loop, but we need to time out after a
+        // while, or the loop will keep running until shutdown.
+        let t0 = performance.now();
+        while (performance.now() - t0 < 5000) {
+            document.getElementById("output").innerText = Math.random();
+        }
+      }
+    </script>
+  </head>
+  <body onload="load()">
+    <p id="output"></p>
+  </body>
+</html>