Train ddc snapshot on itself

utils/dartdevc/BUILD.gn

 # 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.
 
 import("../application_snapshot.gni")
 
 application_snapshot("dartdevc") {
   main_dart = "../../pkg/dev_compiler/bin/dartdevc.dart"
   training_args = [
     "--dart-sdk",
     rebase_path("../../sdk"),
     "--dart-sdk-summary",
     rebase_path("../../pkg/dev_compiler/lib/sdk/ddc_sdk.sum"),
-    "--help",
+    "--library-root",
+    rebase_path("../../pkg/dev_compiler/"),
+    "--unsafe-force-compile",

[Jacob, 2017/02/21 15:28:52]

random idea: can we train it on some large existing package more representative
of real world workloads instead of compiling ddc on itself?
that would allow removing the --unsafe-force-compile arguments and likely make
the training data more representative of real world workloads. For example,
train on the angular package?

+    "-o",
+    "out.js",
+    "../../pkg/dev_compiler/bin/dartdevc.dart",
   ]
   inputs = exec_script("../../tools/list_dart_files.py",
                        [ "absolute",
                          rebase_path("../../pkg/dev_compiler/bin") ],
                        "list lines")
 }