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

sdk/lib/_internal/pub_generated/lib/src/command/downgrade.dart

Index: sdk/lib/_internal/pub_generated/lib/src/command/downgrade.dart
diff --git a/sdk/lib/_internal/pub_generated/lib/src/command/downgrade.dart b/sdk/lib/_internal/pub_generated/lib/src/command/downgrade.dart
new file mode 100644
index 0000000000000000000000000000000000000000..5e340a84a41eb261144ba10ea7dda08f43ea7597
--- /dev/null
+++ b/sdk/lib/_internal/pub_generated/lib/src/command/downgrade.dart
@@ -0,0 +1,57 @@
+library pub.command.downgrade;
+import 'dart:async';
+import '../command.dart';
+import '../log.dart' as log;
+import '../solver/version_solver.dart';
+class DowngradeCommand extends PubCommand {
+  String get description =>
+      "Downgrade the current package's dependencies to oldest versions.\n\n"
+          "This doesn't modify the lockfile, so it can be reset with \"pub get\".";
+  String get usage => "pub downgrade [dependencies...]";
+  bool get takesArguments => true;
+  bool get isOffline => commandOptions['offline'];
+  DowngradeCommand() {
+    commandParser.addFlag(
+        'offline',
+        help: 'Use cached packages instead of accessing the network.');
+    commandParser.addFlag(
+        'dry-run',
+        abbr: 'n',
+        negatable: false,
+        help: "Report what dependencies would change but don't change any.");
+  }
+  Future onRun() {
+    final completer0 = new Completer();
+    scheduleMicrotask(() {
+      try {
+        var dryRun = commandOptions['dry-run'];
+        entrypoint.acquireDependencies(
+            SolveType.DOWNGRADE,
+            useLatest: commandOptions.rest,
+            dryRun: dryRun).then((x0) {
+          try {
+            x0;
+            join0() {
+              completer0.complete(null);
+            }
+            if (isOffline) {
+              log.warning(
+                  "Warning: Downgrading when offline may not update you to "
+                      "the oldest versions of your dependencies.");
+              join0();
+            } else {
+              join0();
+            }
+          } catch (e0) {
+            completer0.completeError(e0);
+          }
+        }, onError: (e1) {
+          completer0.completeError(e1);
+        });
+      } catch (e2) {
+        completer0.completeError(e2);
+      }
+    });
+    return completer0.future;
+  }
+}