Improve output of current-summary gardening tool.

tools/gardening/lib/src/bot.dart

Index: tools/gardening/lib/src/bot.dart
diff --git a/tools/gardening/lib/src/bot.dart b/tools/gardening/lib/src/bot.dart
index 2d5eb3bcb32b7448167a4795d45eaefaa77d054a..9d0af669e1515524a553d2cc06273b177cae765e 100644
--- a/tools/gardening/lib/src/bot.dart
+++ b/tools/gardening/lib/src/bot.dart
@@ -21,6 +21,8 @@ class Bot {
         _client =
             logdog ? new LogdogBuildbotClient() : new HttpBuildbotClient();
 
+  int get mostRecentBuildNumber => _client.mostRecentBuildNumber;
+
   /// Reads the build result of [buildUri] and the [previousCount] earlier
   /// builds.
   Future<List<BuildResult>> readHistoricResults(BuildUri buildUri,
@@ -67,7 +69,7 @@ class Bot {
   List<BuildUri> get mostRecentUris {
     List<BuildUri> result = [];
     for (BuildGroup group in buildGroups) {
-      result.addAll(group.createUris(_client.mostRecentBuildNumber));
+      result.addAll(group.createUris(mostRecentBuildNumber));
     }
     return result;
   }