Update aot_assembly rule to temporarily use --no-preview-dart-2
until it is updated to call gen_kernel to produce a kernel file
before creating the AOT snapshot.

Change-Id: I7e85c3b5189a6ba9ad66fc0c715b4bb3da1b299a
Reviewed-on: https://dart-review.googlesource.com/61082
Reviewed-by: Ryan Macnak <rmacnak@google.com>
Reviewed-by: Zach Anderson <zra@google.com>
diff --git a/utils/application_snapshot.gni b/utils/application_snapshot.gni
index 57e343d..5ed85b2 100644
--- a/utils/application_snapshot.gni
+++ b/utils/application_snapshot.gni
@@ -175,6 +175,9 @@
     abs_output = rebase_path(output, root_build_dir)
 
     vm_args = [
+      # TODO(asiva): For not use --no-preview-dart-2, need to flip this to use
+      # gen_kernel to generate a kernel file before creating an app snapshot.
+      "--no-preview-dart-2",
       "--deterministic",
       "--packages=$dot_packages",
       "--snapshot-kind=app-aot",