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

sdk/lib/_internal/pub_generated/test/get/hosted/get_transitive_test.dart

+library pub_tests;
+import '../../descriptor.dart' as d;
+import '../../test_pub.dart';
+main() {
+  initConfig();
+  integration('gets packages transitively from a pub server', () {
+    servePackages((builder) {
+      builder.serve("foo", "1.2.3", deps: {
+        "bar": "2.0.4"
+      });
+      builder.serve("bar", "2.0.3");
+      builder.serve("bar", "2.0.4");
+      builder.serve("bar", "2.0.5");
+    });
+    d.appDir({
+      "foo": "1.2.3"
+    }).create();
+    pubGet();
+    d.cacheDir({
+      "foo": "1.2.3",
+      "bar": "2.0.4"
+    }).validate();
+    d.packagesDir({
+      "foo": "1.2.3",
+      "bar": "2.0.4"
+    }).validate();
+  });
+}