Restructure YAML package suitable for pub lish

pkg/yaml/test/yaml_test.dart

Index: pkg/yaml/test/yaml_test.dart
diff --git a/utils/tests/pub/yaml_test.dart b/pkg/yaml/test/yaml_test.dart
similarity index 99%
rename from utils/tests/pub/yaml_test.dart
rename to pkg/yaml/test/yaml_test.dart
index 50c021450467b7e4ad7fdf4fa298d971ab018380..b939b674bf6ede166b1ca9f7a9b2ff819e59ff5d 100644
--- a/utils/tests/pub/yaml_test.dart
+++ b/pkg/yaml/test/yaml_test.dart
@@ -4,9 +4,11 @@
 
 library yaml_test;
 
-import '../../../pkg/unittest/lib/unittest.dart';
-import '../../pub/yaml/yaml.dart';
-import '../../pub/yaml/deep_equals.dart';
+import 'package:unittest/unittest.dart';
+import 'package:yaml/yaml.dart';
+import 'package:yaml/deep_equals.dart';
+// TODO(jmesserly): we should not be reaching outside the YAML package
+// The http package has a similar problem.
 import '../../../tests/utils/test_utils.dart';
 
 /// Constructs a new yaml.YamlMap, optionally from a normal Map.