Create an app snapshot of the Dart front end.

runtime/bin/BUILD.gn

Index: runtime/bin/BUILD.gn
diff --git a/runtime/bin/BUILD.gn b/runtime/bin/BUILD.gn
index c3140f0d76a31fff5b21c9b7677f6a0442628b11..c291bd58ce75b75c57dad630a721a45637ff21b6 100644
--- a/runtime/bin/BUILD.gn
+++ b/runtime/bin/BUILD.gn
@@ -489,6 +489,41 @@ action("generate_snapshot_bin") {
   ]
 }
 
+action("generate_dfe_snapshot") {
+  deps = [
+    "../bin:dart($host_toolchain)",
+    "../vm:patched_sdk($host_toolchain)",
+  ]
+
+  package_map = rebase_path("../../.packages")
+  dfe_script = rebase_path("../tools/kernel-service.dart")
+  dfe_snapshot = "$root_out_dir/kernel-service.dart.snapshot"
+  training_script =
+      "file://" + rebase_path("../../pkg/compiler/lib/src/dart2js.dart")
+  dart_dir = get_label_info("../bin:dart($host_toolchain)", "root_out_dir")
+  dart_path = rebase_path("$dart_dir/dart")
+
+  inputs = [
+    package_map,
+    dfe_script,
+  ]
+
+  outputs = [
+    dfe_snapshot,
+  ]
+
+  script = rebase_path("../../build/gn_run_binary.py")
+  args = [
+    "exec_script",
+    dart_path,
+    "--snapshot=" + rebase_path(dfe_snapshot),
+    "--snapshot-kind=app-jit",
+    "--packages=" + package_map,
+    dfe_script,
+    training_script,
+  ]
+}
+
 action("generate_snapshot_file") {
   deps = [
     ":generate_snapshot_bin",