Don't load transformers that aren't going to be used for an executable.

sdk/lib/_internal/pub_generated/lib/src/entrypoint.dart

Index: sdk/lib/_internal/pub_generated/lib/src/entrypoint.dart
diff --git a/sdk/lib/_internal/pub_generated/lib/src/entrypoint.dart b/sdk/lib/_internal/pub_generated/lib/src/entrypoint.dart
index 1fa5a0e9aa04813b36ca0791fdb231a1183d9d28..eadf9a997c76aec1888035644eb5d7fcd0ff9d6b 100644
--- a/sdk/lib/_internal/pub_generated/lib/src/entrypoint.dart
+++ b/sdk/lib/_internal/pub_generated/lib/src/entrypoint.dart
@@ -314,10 +314,13 @@ class Entrypoint {
                             var packagesToLoad = unionAll(
                                 executables.keys.map(
                                     graph.transitiveDependencies)).map(((package) => package.name)).toSet();
+                            var executableIds =
+                                unionAll(executables.values.map(((ids) => ids.toSet())));
                             AssetEnvironment.create(
                                 this,
                                 BarbackMode.RELEASE,
                                 packages: packagesToLoad,
+                                entrypoints: executableIds,
                                 useDart2JS: false).then((x0) {
                               try {
                                 var environment = x0;