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

sdk/lib/_internal/pub_generated/test/barback/subdirectories_test.dart

+import 'package:path/path.dart' as p;
+import 'package:scheduled_test/scheduled_test.dart';
+import '../descriptor.dart' as d;
+import '../serve/utils.dart';
+import '../test_pub.dart';
+main() {
+  initConfig();
+  setUp(() {
+    d.dir(
+        appPath,
+        [
+            d.appPubspec(),
+            d.dir(
+                "web",
+                [
+                    d.dir("one", [d.dir("inner", [d.file("file.txt", "one")])]),
+                    d.dir("two", [d.dir("inner", [d.file("file.txt", "two")])]),
+                    d.dir("nope", [d.dir("inner", [d.file("file.txt", "nope")])])])]).create();
+  });
+  var webOne = p.join("web", "one");
+  var webTwoInner = p.join("web", "two", "inner");
+  integration("builds subdirectories", () {
+    schedulePub(
+        args: ["build", webOne, webTwoInner],
+        output: new RegExp(r'Built 2 files to "build".'));
+    d.dir(
+        appPath,
+        [
+            d.dir(
+                "build",
+                [
+                    d.dir(
+                        "web",
+                        [
+                            d.dir("one", [d.dir("inner", [d.file("file.txt", "one")])]),
+                            d.dir("two", [d.dir("inner", [d.file("file.txt", "two")])]),
+                            d.nothing("nope")])])]).validate();
+  });
+  integration("serves subdirectories", () {
+    pubServe(args: [webOne, webTwoInner]);
+    requestShouldSucceed("inner/file.txt", "one", root: webOne);
+    requestShouldSucceed("file.txt", "two", root: webTwoInner);
+    expectNotServed("web");
+    expectNotServed(p.join("web", "three"));
+    endPubServe();
+  });
+}