[dart-pkg] Add package:expect to roots

Change-Id: If39a88ad77c845fc540e73c45d4e09f3fd9222cc

dart/update_3p_packages.py

diff --git a/dart/update_3p_packages.py b/dart/update_3p_packages.py
index 219c7d4..fa809c4 100755
--- a/dart/update_3p_packages.py
+++ b/dart/update_3p_packages.py
@@ -16,6 +16,7 @@
 ROOT_PUBSPECS = [
     'third_party/dart/pkg/analyzer',
     'third_party/dart/pkg/build_integration',
+    'third_party/dart/pkg/expect',
     'third_party/dart/pkg/front_end',
     'third_party/dart/pkg/kernel',
     'third_party/dart/pkg/testing',