add scroll test

e2e/ambassador/src/content/scrolls.js

@@ -0,0 +1,18 @@
+const get = () => {
+  let element = document.documentElement;
+  return {
+    xMax: element.scrollWidth - element.clientWidth,
+    yMax: element.scrollHeight - element.clientHeight,
+    x: element.scrollLeft,
+    y: element.scrollTop,
+  };
+};
+
+const set = (x, y) => {
+  let element = document.documentElement;
+  element.scrollLeft = x;
+  element.scrollTop = y;
+  return get();
+};
+
+export { get, set };