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

sdk/lib/_internal/pub_generated/test/cache/add/adds_latest_matching_version_test.dart

+library pub_tests;
+import '../../descriptor.dart' as d;
+import '../../test_pub.dart';
+main() {
+  initConfig();
+  integration(
+      'adds the latest version of the package matching the ' 'version constraint',
+      () {
+    servePackages((builder) {
+      builder.serve("foo", "1.2.2");
+      builder.serve("foo", "1.2.3");
+      builder.serve("foo", "2.0.0-dev");
+      builder.serve("foo", "2.0.0");
+    });
+    schedulePub(
+        args: ["cache", "add", "foo", "-v", ">=1.0.0 <2.0.0"],
+        output: 'Downloading foo 1.2.3...');
+    d.cacheDir({
+      "foo": "1.2.3"
+    }).validate();
+    d.hostedCache(
+        [
+            d.nothing("foo-1.2.2"),
+            d.nothing("foo-2.0.0-dev"),
+            d.nothing("foo-2.0.0")]).validate();
+  });
+}