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

utils/compiler/create_snapshot_entry.dart

 // Copyright (c) 2013, 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 'dart:io';
 
 Future<String> getVersion(var rootPath) {
   var suffix = Platform.operatingSystem == 'windows' ? '.exe' : '';
   var printVersionScript = rootPath.resolve("tools/print_version.py");
   return Process.run("python$suffix",
@@ skipping 43 matching lines @@
   });
 }
 
 void writeSnapshotFile(var path, var content) {
     File file = new File(path);
     var writer = file.openSync(mode: FileMode.WRITE);
     writer.writeStringSync(content);
     writer.close();
 }
 
-Future createSnapshot(var dart_file) {
-  return Process.run(Platform.executable,
-                     ["--packages=../../.packages",
-                      "--snapshot=$dart_file.snapshot",
-                      dart_file])
-      .then((result) {
-        if (result.exitCode != 0) {
-          print("Could not generate snapshot: result code ${result.exitCode}");
-          print(result.stdout);
-          print(result.stderr);
-          throw "Could not generate snapshot";
-        }
-      });
-}
-
 /**
  * Takes the following arguments:
  * --output_dir=val     The full path to the output_dir.
  * --dart2js_main=val   The path to the dart2js main script relative to root.
  */
 void main(List<String> arguments) {
   var validArguments = ["--output_dir", "--dart2js_main"];
   var args = {};
   for (var argument in arguments) {
     var argumentSplit = argument.split("=");
     if (argumentSplit.length != 2) throw "Invalid argument $argument, no =";
     if (!validArguments.contains(argumentSplit[0])) {
       throw "Invalid argument $argument";
     }
     args[argumentSplit[0].substring(2)] = argumentSplit[1];
   }
   if (!args.containsKey("dart2js_main")) throw "Please specify dart2js_main";
   if (!args.containsKey("output_dir")) throw "Please specify output_dir";
 
   var scriptFile = Uri.base.resolveUri(Platform.script);
   var path = scriptFile.resolve(".");
   var rootPath = path.resolve("../..");
   getSnapshotGenerationFile(args, rootPath).then((result) {
     var wrapper = "${args['output_dir']}/utils_wrapper.dart";
     writeSnapshotFile(wrapper, result);
-    createSnapshot(wrapper);
   });
 
   getDart2jsSnapshotGenerationFile(args, rootPath).then((result) {
     var wrapper = "${args['output_dir']}/dart2js.dart";
     writeSnapshotFile(wrapper, result);
-    createSnapshot(wrapper);
   });
-
 }