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

sdk/lib/_internal/pub_generated/test/get/path/no_pubspec_test.dart

+import 'package:path/path.dart' as path;
+import '../../descriptor.dart' as d;
+import '../../test_pub.dart';
+main() {
+  initConfig();
+  integration('path dependency to non-package directory', () {
+    d.dir('foo').create();
+    var fooPath = path.join(sandboxDir, "foo");
+    d.dir(appPath, [d.appPubspec({
+        "foo": {
+          "path": fooPath
+        }
+      })]).create();
+    pubGet(
+        error: new RegExp(
+            r'Could not find a file named "pubspec.yaml" ' r'in "[^\n]*"\.'));
+  });
+}