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

sdk/lib/_internal/pub_generated/test/cache/repair/reinstalls_git_packages_test.dart

+library pub_tests;
+import 'package:path/path.dart' as path;
+import 'package:scheduled_test/scheduled_test.dart';
+import '../../../lib/src/io.dart';
+import '../../descriptor.dart' as d;
+import '../../test_pub.dart';
+main() {
+  initConfig();
+  integration('reinstalls previously cached git packages', () {
+    d.git('foo.git', [d.libDir('foo'), d.libPubspec('foo', '1.0.0')]).create();
+    d.appDir({
+      "foo": {
+        "git": "../foo.git"
+      }
+    }).create();
+    pubGet();
+    d.git('foo.git', [d.libDir('foo'), d.libPubspec('foo', '1.0.1')]).commit();
+    pubUpgrade();
+    var fooDirs;
+    schedule(() {
+      var gitCacheDir = path.join(sandboxDir, cachePath, "git");
+      fooDirs = listDir(
+          gitCacheDir).where((dir) => path.basename(dir).startsWith("foo-")).toList();
+      for (var dir in fooDirs) {
+        deleteEntry(path.join(dir, "lib", "foo.dart"));
+      }
+    });
+    schedulePub(args: ["cache", "repair"], output: '''
+          Resetting Git repository for foo 1.0.0...
+          Resetting Git repository for foo 1.0.1...
+          Reinstalled 2 packages.''');
+    schedule(() {
+      var fooLibs = fooDirs.map((dir) {
+        var fooDirName = path.basename(dir);
+        return d.dir(
+            fooDirName,
+            [d.dir("lib", [d.file("foo.dart", 'main() => "foo";')])]);
+      }).toList();
+      d.dir(cachePath, [d.dir("git", fooLibs)]).validate();
+    });
+  });
+}