Roll Observatory packages and add a roll script

packages/charted/test.disabled/core/core_test.dart

+/*
+ * Copyright 2014 Google Inc. All rights reserved.
+ *
+ * Use of this source code is governed by a BSD-style
+ * license that can be found in the LICENSE file or at
+ * https://developers.google.com/open-source/licenses/bsd
+ */
+
+library charted.test.core;
+
+import 'dart:html' show document, Element;
+import 'package:unittest/unittest.dart';
+import 'package:charted/core/utils.dart';
+
+import 'dart:math' as math;
+
+part 'lists_test.dart';
+part 'namespace_test.dart';
+part 'color_test.dart';
+part 'math_test.dart';
+part 'object_factory_test.dart';
+
+coreTests() {
+  group('isNullOrEmpty()', () {
+    test('returns true when the object is null or empty', () {
+      expect(isNullOrEmpty(null), isTrue);
+      expect(isNullOrEmpty(''), isTrue);
+      expect(isNullOrEmpty({}), isTrue);
+      expect(isNullOrEmpty([]), isTrue);
+    });
+    test('returns false when the object is not null or empty', () {
+      expect(isNullOrEmpty([3]), isFalse);
+    });
+  });
+
+  testLists();
+  testNamespace();
+  testColor();
+  testMath();
+  testObjectFactory();
+}