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

sdk/lib/_internal/pub_generated/test/serve/gets_first_if_dependency_version_changed_test.dart

+library pub_tests;
+import '../descriptor.dart' as d;
+import '../test_pub.dart';
+import 'utils.dart';
+main() {
+  initConfig();
+  integration(
+      "gets first if a dependency's version doesn't match the one in "
+          "the lock file",
+      () {
+    d.dir("foo", [d.libPubspec("foo", "0.0.1"), d.libDir("foo")]).create();
+    d.appDir({
+      "foo": {
+        "path": "../foo",
+        "version": "0.0.1"
+      }
+    }).create();
+    pubGet();
+    d.appDir({
+      "foo": {
+        "path": "../foo",
+        "version": "0.0.2"
+      }
+    }).create();
+    d.dir("foo", [d.libPubspec("foo", "0.0.2"), d.libDir("foo")]).create();
+    pubServe(shouldGetFirst: true);
+    requestShouldSucceed("packages/foo/foo.dart", 'main() => "foo";');
+    endPubServe();
+  });
+}