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

sdk/lib/_internal/pub_generated/test/snapshot/creates_a_snapshot_test.dart

+library pub_tests;
+import 'package:path/path.dart' as p;
+import 'package:scheduled_test/scheduled_test.dart';
+import '../descriptor.dart' as d;
+import '../test_pub.dart';
+main() {
+  initConfig();
+  integration(
+      "creates a snapshot for an immediate dependency's executables",
+      () {
+    servePackages((builder) {
+      builder.serve(
+          "foo",
+          "1.2.3",
+          contents: [
+              d.dir(
+                  "bin",
+                  [
+                      d.file("hello.dart", "void main() => print('hello!');"),
+                      d.file("goodbye.dart", "void main() => print('goodbye!');"),
+                      d.file("shell.sh", "echo shell"),
+                      d.dir("subdir", [d.file("sub.dart", "void main() => print('sub!');")])])]);
+    });
+    d.appDir({
+      "foo": "1.2.3"
+    }).create();
+    pubGet(
+        output: allOf(
+            [contains("Precompiled foo:hello."), contains("Precompiled foo:goodbye.")]));
+    d.dir(
+        p.join(appPath, '.pub', 'bin'),
+        [
+            d.file('sdk-version', '0.1.2+3\n'),
+            d.dir(
+                'foo',
+                [
+                    d.matcherFile('hello.dart.snapshot', contains('hello!')),
+                    d.matcherFile('goodbye.dart.snapshot', contains('goodbye!')),
+                    d.nothing('shell.sh.snapshot'),
+                    d.nothing('subdir')])]).validate();
+    var process = pubRun(args: ['foo:hello']);
+    process.stdout.expect("hello!");
+    process.shouldExit();
+    process = pubRun(args: ['foo:goodbye']);
+    process.stdout.expect("goodbye!");
+    process.shouldExit();
+  });
+}