diff --git a/dom/security/test/general/file_same_site_cookies_about.sjs b/dom/security/test/general/file_same_site_cookies_about.sjs
new file mode 100644
index 000000000000..715fac06fd63
--- /dev/null
+++ b/dom/security/test/general/file_same_site_cookies_about.sjs
@@ -0,0 +1,61 @@
+// Custom *.sjs file specifically for the needs of Bug 1454721
+
+// small red image
+const IMG_BYTES = atob(
+ "iVBORw0KGgoAAAANSUhEUgAAAAUAAAAFCAYAAACNbyblAAAAHElEQVQI12" +
+ "P4//8/w38GIAXDIBKE0DHxgljNBAAO9TXL0Y4OHwAAAABJRU5ErkJggg==");
+
+const IFRAME_INC =
+ ``;
+
+function handleRequest(request, response)
+{
+ // avoid confusing cache behaviors
+ response.setHeader("Cache-Control", "no-cache", false);
+
+ // using startsWith and discard the math random
+ if (request.queryString.startsWith("setSameSiteCookie")) {
+ response.setHeader("Set-Cookie", "myKey=mySameSiteAboutCookie; samesite=strict", true);
+ response.setHeader("Content-Type", "image/png");
+ response.write(IMG_BYTES);
+ return;
+ }
+
+ // navigation tests
+ if (request.queryString === "loadsrcdocframeNav") {
+ let FRAME = `
+ `;
+ response.write(FRAME);
+ return;
+ }
+
+ if (request.queryString === "loadblankframeNav") {
+ let FRAME = `
+ `;
+ response.write(FRAME);
+ return;
+ }
+
+ // inclusion tets
+ if (request.queryString === "loadsrcdocframeInc") {
+ response.write("");
+ return;
+ }
+
+ if (request.queryString === "loadblankframeInc") {
+ let FRAME = `
+
+
+
+