Support activating packages from local paths.

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

Index: sdk/lib/_internal/pub/test/global/activate/constraint_with_path_test.dart
diff --git a/sdk/lib/_internal/pub/test/global/activate/bad_version_test.dart b/sdk/lib/_internal/pub/test/global/activate/constraint_with_path_test.dart
similarity index 52%
copy from sdk/lib/_internal/pub/test/global/activate/bad_version_test.dart
copy to sdk/lib/_internal/pub/test/global/activate/constraint_with_path_test.dart
index 1bf2eeaa85db5a4f97f44404de7780bdf91aaeea..68f2ac385d558c6df1c2a77c58f1f461d75e8b5f 100644
--- a/sdk/lib/_internal/pub/test/global/activate/bad_version_test.dart
+++ b/sdk/lib/_internal/pub/test/global/activate/constraint_with_path_test.dart
@@ -7,13 +7,15 @@ import '../../test_pub.dart';
 
 main() {
   initConfig();
-  integration('fails if the version constraint cannot be parsed', () {
-    schedulePub(args: ["global", "activate", "foo", "1.0"],
+  integration('fails if a version is passed with the path source', () {
+    schedulePub(args: ["global", "activate", "-spath", "foo", "1.2.3"],
         error: """
-            Could not parse version "1.0". Unknown text at "1.0".
+            Unexpected argument "1.2.3".
 
-            Usage: pub global activate <package> [version]
-            -h, --help    Print usage information for this command.
+            Usage: pub global activate <package...>
+            -h, --help      Print usage information for this command.
+            -s, --source    The source used to find the package.
+                            [hosted (default), path]
 
             Run "pub help" to see global options.
             """,