Add dart:io view to the observatory.

runtime/bin/service_object_patch.dart

Index: runtime/bin/service_object_patch.dart
diff --git a/runtime/bin/service_object_patch.dart b/runtime/bin/service_object_patch.dart
index f23dd71b472627838b9014dd27fcc7c7e45375a8..b67059820f398fabefd22bb2aa9ce12a39d8d409 100644
--- a/runtime/bin/service_object_patch.dart
+++ b/runtime/bin/service_object_patch.dart
@@ -17,7 +17,7 @@ String _serviceObjectHandler(List<String> paths,
     throw "Invalid path '${paths.join("/")}'";
   }
   if (paths.isEmpty) {
-    badPath();
+    return JSON.encode(_ioServiceObject());
   }
   int i = 0;
   var current = _servicePathMap;
@@ -35,6 +35,15 @@ String _serviceObjectHandler(List<String> paths,
   return JSON.encode(current(paths.sublist(i)));
 }
 
+Map _ioServiceObject() {
+  return {
+    'id': 'io',
+    'type': 'IO',
+    'name': 'io',
+    'user_name': 'io',
+  };
+}
+
 Map _httpServersServiceObject(args) {
   if (args.length == 1) {
     var server = _HttpServer._servers[int.parse(args.first)];