Update pub to look for VM's new error message text.

sdk/lib/_internal/pub_generated/test/transformer/fails_to_load_a_transform_with_an_import_error_test.dart

Index: sdk/lib/_internal/pub_generated/test/transformer/fails_to_load_a_transform_with_an_import_error_test.dart
diff --git a/sdk/lib/_internal/pub_generated/test/transformer/fails_to_load_a_transform_with_an_import_error_test.dart b/sdk/lib/_internal/pub_generated/test/transformer/fails_to_load_a_transform_with_an_import_error_test.dart
index 6b6df1016a700831d8bbd938a4b95133b0f02453..3f68f63bb3ffde79d865e5e81e083537ff0d92a4 100644
--- a/sdk/lib/_internal/pub_generated/test/transformer/fails_to_load_a_transform_with_an_import_error_test.dart
+++ b/sdk/lib/_internal/pub_generated/test/transformer/fails_to_load_a_transform_with_an_import_error_test.dart
@@ -31,7 +31,8 @@ main() {
       createLockFile('myapp', pkg: ['barback']);
       var pub = startPubServe();
       pub.stderr.expect("Unhandled exception:");
-      pub.stderr.expect(startsWith("Uncaught Error: Failure getting "));
+      pub.stderr.expect(
+          startsWith("Uncaught Error: Load Error: Failure getting "));
       pub.shouldExit(1);
     });
   });