Don't load assets unnecessarily when precompiling executables.

sdk/lib/_internal/pub/test/no_package_symlinks_test.dart

Index: sdk/lib/_internal/pub/test/no_package_symlinks_test.dart
diff --git a/sdk/lib/_internal/pub/test/no_package_symlinks_test.dart b/sdk/lib/_internal/pub/test/no_package_symlinks_test.dart
index 12d51514569244f30441556ba3b903dea8f8419e..2911debcd450615958d44d59e18ef29485d72c71 100644
--- a/sdk/lib/_internal/pub/test/no_package_symlinks_test.dart
+++ b/sdk/lib/_internal/pub/test/no_package_symlinks_test.dart
@@ -13,10 +13,10 @@ main() {
   forBothPubGetAndUpgrade((command) {
     group("with --no-package-symlinks", () {
       integration("installs hosted dependencies to the cache", () {
-        servePackages([
-          packageMap("foo", "1.0.0"),
-          packageMap("bar", "1.0.0")
-        ]);
+        servePackages((builder) {
+          builder.serve("foo", "1.0.0");
+          builder.serve("bar", "1.0.0");
+        });
 
         d.appDir({"foo": "any", "bar": "any"}).create();