Use timeout to read most recent build from http

tools/gardening/lib/src/buildbot_loading.dart

Index: tools/gardening/lib/src/buildbot_loading.dart
diff --git a/tools/gardening/lib/src/buildbot_loading.dart b/tools/gardening/lib/src/buildbot_loading.dart
index 6767bd01eeb50f01267cc8f943240cc1b19d4eb5..93bd62cf3110d39a255d952b8434739896dd0d31 100644
--- a/tools/gardening/lib/src/buildbot_loading.dart
+++ b/tools/gardening/lib/src/buildbot_loading.dart
@@ -33,11 +33,12 @@ Future<BuildResult> _readBuildResult(
 
 /// Fetches test data for [buildUri] through the buildbot stdio.
 Future<BuildResult> readBuildResultFromHttp(
-    HttpClient client, BuildUri buildUri) {
+    HttpClient client, BuildUri buildUri,
+    [Duration timeout]) {
   Future<String> read() async {
     Uri uri = buildUri.toUri();
     log('Reading buildbot results: $uri');
-    return readUriAsText(client, uri);
+    return readUriAsText(client, uri, timeout);
   }
 
   return _readBuildResult(buildUri, read);