Store the async-await compiled pub code directly in the repo.

sdk/lib/_internal/pub_generated/test/run/includes_parent_directories_of_entrypoint_test.dart

+import 'package:path/path.dart' as path;
+import '../descriptor.dart' as d;
+import '../test_pub.dart';
+const SCRIPT = r"""
+import '../../a.dart';
+import '../b.dart';
+main() {
+  print("$a $b");
+}
+""";
+main() {
+  initConfig();
+  integration(
+      'allows assets in parent directories of the entrypoint to be' 'accessed',
+      () {
+    d.dir(
+        appPath,
+        [
+            d.appPubspec(),
+            d.dir(
+                "tool",
+                [
+                    d.file("a.dart", "var a = 'a';"),
+                    d.dir(
+                        "a",
+                        [
+                            d.file("b.dart", "var b = 'b';"),
+                            d.dir("b", [d.file("app.dart", SCRIPT)])])])]).create();
+    var pub = pubRun(args: [path.join("tool", "a", "b", "app")]);
+    pub.stdout.expect("a b");
+    pub.shouldExit();
+  });
+}