Add supporting themes required for Lotusdocs

themes/hugo-mod-jslibs-dist/popperjs/package/lib/dom-utils/getWindowScroll.js.flow

@@ -0,0 +1,14 @@
+// @flow
+import getWindow from './getWindow';
+import type { Window } from '../types';
+
+export default function getWindowScroll(node: Node | Window) {
+  const win = getWindow(node);
+  const scrollLeft = win.pageXOffset;
+  const scrollTop = win.pageYOffset;
+
+  return {
+    scrollLeft,
+    scrollTop,
+  };
+}