Add a "global activate" command to pub.

sdk/lib/_internal/pub/test/lock_file_test.dart

Index: sdk/lib/_internal/pub/test/lock_file_test.dart
diff --git a/sdk/lib/_internal/pub/test/lock_file_test.dart b/sdk/lib/_internal/pub/test/lock_file_test.dart
index 85724e46ffdff0725973414e5eec90d5fcaccacc..c6c5a229f96001042ca307027374fc3b940445bc 100644
--- a/sdk/lib/_internal/pub/test/lock_file_test.dart
+++ b/sdk/lib/_internal/pub/test/lock_file_test.dart
@@ -23,11 +23,8 @@ class MockSource extends Source {
   Future<Pubspec> doDescribe(PackageId id) => throw new UnsupportedError(
       "Cannot describe mock packages.");
 
-  Future ensureLocal(PackageId id) => throw new UnsupportedError(
-      "Cannot get a mock package.");
-
   Future get(PackageId id, String symlink) => throw new UnsupportedError(
-      "Cannot get an mock.");
+      "Cannot get a mock package.");
 
   Future<String> getDirectory(PackageId id) => throw new UnsupportedError(
       "Cannot get the directory for mock packages.");