In summary/stats.dart, don't count enums with index == 0.

pkg/analyzer/tool/summary/stats.dart

Index: pkg/analyzer/tool/summary/stats.dart
diff --git a/pkg/analyzer/tool/summary/stats.dart b/pkg/analyzer/tool/summary/stats.dart
index 6d6f10b147a76dd223adb1f8313e927e6f619a5f..da524a0547535ac8871609d2c5dea928926b9a95 100644
--- a/pkg/analyzer/tool/summary/stats.dart
+++ b/pkg/analyzer/tool/summary/stats.dart
@@ -9,6 +9,7 @@
 library analyzer.tool.summary.stats;
 
 import 'dart:io';
+import 'dart:mirrors';
 
 import 'package:analyzer/src/summary/base.dart';
 import 'package:analyzer/src/summary/idl.dart';
@@ -80,7 +81,8 @@ class Stats {
           value == 0 ||
           value == false ||
           value == '' ||
-          value is List && value.isEmpty) {
+          value is List && value.isEmpty ||
+          reflect(value).type.isEnum && (value as dynamic).index == 0) {
         return;
       }
       if (!typeCounts.containsKey(key)) {