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

sdk/lib/_internal/pub_generated/test/dart2js/allows_import_in_dart_code_test.dart

+import 'package:scheduled_test/scheduled_test.dart';
+import '../descriptor.dart' as d;
+import '../test_pub.dart';
+import '../serve/utils.dart';
+main() {
+  initConfig();
+  integration("handles imports in the Dart code", () {
+    d.dir(
+        "foo",
+        [d.libPubspec("foo", "0.0.1"), d.dir("lib", [d.file("foo.dart", """
+library foo;
+foo() => 'footext';
+""")])]).create();
+    d.dir(appPath, [d.appPubspec({
+        "foo": {
+          "path": "../foo"
+        }
+      }), d.dir("lib", [d.file("lib.dart", """
+library lib;
+lib() => 'libtext';
+""")]), d.dir("web", [d.file("main.dart", """
+import 'package:foo/foo.dart';
+import 'package:myapp/lib.dart';
+void main() {
+  print(foo());
+  print(lib());
+}
+""")])]).create();
+    pubServe(shouldGetFirst: true);
+    requestShouldSucceed("main.dart.js", contains("footext"));
+    requestShouldSucceed("main.dart.js", contains("libtext"));
+    endPubServe();
+  });
+}