Hard fail on ddc sdk build error

pkg/dev_compiler/tool/build_sdk.dart

 #!/usr/bin/env dart
 // 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.
 
 /// A straightforward script that builds the SDK.
 ///
 /// This would be easy enough to do in a shell script, as we go through the
 /// command line interface. But being able to build from a Dart library means
 /// we can call this during code coverage to get more realistic numbers.
@@ skipping 33 matching lines @@
     'dart:mirrors',
     'dart:typed_data',
     'dart:indexed_db',
     'dart:html',
     'dart:html_common',
     'dart:svg',
     'dart:web_audio',
     'dart:web_gl',
     'dart:web_sql'
   ]);
-  compile(args);
+
+  if (compile(args) != 0) {
+    throw 'SDK build failed.';

[Jennifer Messerly, 2017/01/21 00:55:27]

you don't need a throw. You can just return here, that will set the exit code.

The lack of "return" was most likely an oversight.

+  }
 }