import FIREFOX_52_6_0esr_RELEASE from mozilla-esr52 hg repo

layout/generic/test/file_SlowImage.sjs

@@ -0,0 +1,45 @@
+"use strict";
+const Cc = Components.classes;
+const Ci = Components.interfaces;
+
+const IMG_BYTES = atob(
+  "iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAA" +
+  "DUlEQVQImWNgY2P7DwABOgESJhRQtgAAAABJRU5ErkJggg==");
+
+function handleRequest(request, response) {
+  response.processAsync();
+  getObjectState("context", function(obj) {
+    let ctx;
+    if (obj == null) {
+      ctx = {
+        QueryInterface: function(iid) {
+          if (iid.equals(Components.interfaces.nsISupports))
+            return this;
+          throw Components.results.NS_ERROR_NO_INTERFACE;
+        }
+      };
+      ctx.wrappedJSObject = ctx;
+
+      ctx.promise = new Promise(resolve => {
+        ctx.resolve = resolve;
+      });
+
+      setObjectState("context", ctx);
+    } else {
+      ctx = obj.wrappedJSObject;
+    }
+    Promise.resolve(ctx).then(next);
+  });
+
+  function next(ctx) {
+    if (request.queryString.indexOf("continue") >= 0) {
+      ctx.resolve();
+    }
+
+    ctx.promise.then(() => {
+      response.setHeader("Content-Type", "image/png");
+      response.write(IMG_BYTES);
+      response.finish();
+    });
+  }
+}