Sitemap query now fully asynchronous

Sitemap generation is now independent from the navbar generation, and
it will be added to the navbar only once the navbar has been created.

Also, better style for code.

web/dart/main.dart

@@ -1,9 +1,9 @@
 import './reorganize_html.dart' show reorganizeHtml;
 import './theme.dart' show enableThemeChanger, setTheme;
+import './parse_sitemap.dart' show getSitemap;
 
 Future<void> main() async {
   await setTheme();
-  await reorganizeHtml().then((_) {
+  await reorganizeHtml().then((_) => enableThemeChanger());
-    enableThemeChanger();
+  await getSitemap();
-  });
 }

web/dart/navbar.dart

@@ -28,18 +28,6 @@ Future<Element> makePages() async {
   var pages = Element.ul()
     ..attributes['id'] = 'drop-page'
     ..classes.add('dropdown');
-  await parseSitemap().then((final sitemap) => {
-        sitemap.forEach((url, name) {
-          final link = Element.li()
-            ..classes.add('dropdown-item')
-            ..insertAdjacentElement(
-                'afterBegin',
-                Element.a()
-                  ..attributes['href'] = url
-                  ..innerText = name);
-          pages.insertAdjacentElement('beforeEnd', link);
-        })
-      });
   return Element.li()
     ..append(Element.a()
       ..attributes['href'] = 'javascript:void(0)'

web/dart/parse_sitemap.dart

@@ -1,15 +1,15 @@
-import 'dart:html' show HttpRequest;
+import 'dart:html' as html show HttpRequest, Element, querySelector;
 
 import 'package:html/parser.dart' show parse;
-import 'package:html/dom.dart' show Element;
+import 'package:html/dom.dart' as dom show Element;
 
 final excluded_keywords = ['index', 'CONTRIBUTING', 'LICENSE', 'README'];
 
 // Get the sitemap content
-Future<String> getSitemap() async {
+Future<String> fetchRemoteSitemap() async {
   const path = 'sitemap.html';
   try {
-    return await HttpRequest.getString(path);
+    return await html.HttpRequest.getString(path);
   } catch (e) {
     print('Couldn’t open $path');
   }
@@ -17,7 +17,7 @@ Future<String> getSitemap() async {
 }
 
 // Parse the list of elements and detect pages from this list
-Map<String, String> detectPages(List<Element> sitemap, [String prefix]) {
+Map<String, String> detectPages(List<dom.Element> sitemap, [String prefix]) {
   final links = <String, String>{};
   for (var elem in sitemap) {
     for (var kw in excluded_keywords) {
@@ -42,7 +42,30 @@ Map<String, String> detectPages(List<Element> sitemap, [String prefix]) {
 // This function returns a Map which contains all links to languages detected
 // from the sitemap.
 Future<Map<String, String>> parseSitemap() async {
-  final content = await getSitemap();
+  final content = await fetchRemoteSitemap();
   final sitemap = parse(content).getElementsByClassName('org-ul')[0].children;
   return detectPages(sitemap);
 }
+
+Future sleep(Duration time) async {
+  return Future.delayed(time);
+}
+
+Future<html.Element> getSitemap() async {
+  final sitemap = await parseSitemap();
+  final pages = <html.Element>[];
+  sitemap.forEach((url, name) {
+    final link = html.Element.li()
+      ..classes.add('dropdown-item')
+      ..append(html.Element.a()
+        ..attributes['href'] = url
+        ..innerText = name);
+    pages.add(link);
+  });
+  var drop_container;
+  do {
+    await sleep(Duration(seconds: 1));
+    drop_container = html.querySelector('#drop-page');
+  } while (drop_container != null);
+  pages.forEach((link) => drop_container.append(link));
+}