GN: Build the SDK with app snapshots instead of script snapshots.

utils/invoke_dart.gni

 # Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
 # for details. All rights reserved. Use of this source code is governed by a
 # BSD-style license that can be found in the LICENSE file.
 
 _dart_root = rebase_path("..")
 
 template("invoke_dart") {
   assert(defined(invoker.outputs), "invoke_dart must specify outputs")
   extra_deps = []
   if (defined(invoker.deps)) {
@@ skipping 32 matching lines @@
 
     script = "$_dart_root/tools/dart_for_gn.py"
     args = [
       dart,
     ] + extra_args
   }
 }
 
 template("application_snapshot") {
   assert(defined(invoker.main_dart), "Must specify 'main_dart'")
+  assert(defined(invoker.training_args), "Must specify 'training_args'")
   main_dart = invoker.main_dart
+  training_args = invoker.training_args
   name = target_name
   if (defined(invoker.name)) {
     name = invoker.name
   }
   extra_deps = []
   if (defined(invoker.deps)) {
     extra_deps += invoker.deps
   }
   extra_inputs = []
   if (defined(invoker.inputs)) {
@@ skipping 14 matching lines @@
       output,
     ]
 
     dot_packages = rebase_path("$_dart_root/.packages")
     abs_output = rebase_path(output)
     main_file = rebase_path(main_dart)
 
     args = [
       "--packages=$dot_packages",
       "--snapshot=$abs_output",
-      main_file
-    ]
+      "--snapshot-kind=app-jit",
+      main_file,
+    ] + training_args
   }
 }