Support activating packages from local paths.

sdk/lib/_internal/pub/test/global/activate/no_package_at_path_test.dart

Index: sdk/lib/_internal/pub/test/global/activate/no_package_at_path_test.dart
diff --git a/sdk/lib/_internal/pub/test/global/activate/no_package_at_path_test.dart b/sdk/lib/_internal/pub/test/global/activate/no_package_at_path_test.dart
new file mode 100644
index 0000000000000000000000000000000000000000..3ea7fb45ceca047366c9f7be6c64ab62c7d97665
--- /dev/null
+++ b/sdk/lib/_internal/pub/test/global/activate/no_package_at_path_test.dart
@@ -0,0 +1,18 @@
+// Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import '../../descriptor.dart' as d;
+import '../../test_pub.dart';
+
+main() {
+  initConfig();
+  integration('fails if path does not point to a package', () {
+    // No pubspec.
+    d.dir("foo", []).create();
+
+    schedulePub(args: ["global", "activate", "--source", "path", "foo"],
+        error: 'Could not find a file named "pubspec.yaml" in "foo".',
+        exitCode: 1);
+  });
+}