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

sdk/lib/_internal/pub_generated/test/global/run/runs_script_test.dart

+import '../../descriptor.dart' as d;
+import '../../test_pub.dart';
+main() {
+  initConfig();
+  integration('runs a script in an activated package', () {
+    servePackages((builder) {
+      builder.serve(
+          "foo",
+          "1.0.0",
+          contents: [
+              d.dir("bin", [d.file("script.dart", "main(args) => print('ok');")])]);
+    });
+    schedulePub(args: ["global", "activate", "foo"]);
+    var pub = pubRun(global: true, args: ["foo:script"]);
+    pub.stdout.expect("ok");
+    pub.shouldExit();
+  });
+}