Fix field override error

Fix field override error

This fixes the following error reported by https://codereview.chromium.org/1430953004/ (not landed yet):

severe: [InvalidFieldOverride] Field declaration _ControllerSubscription<T>._controller cannot be overridden in _BroadcastSubscription. (dart:async/broadcast_stream_controller.dart, line 40, col 3)

Devon: this should address https://github.com/flutter/atom-flutter-dev/issues/2

R=leafp@google.com

Committed: https://github.com/dart-lang/dev_compiler/commit/927028ec663ba544ee39d8b137c88f0ea65285d5

[vsm, 2015-11-06 15:12:58]

Description was changed from

==========
Fix field override error

This fixes the following error reported by
https://codereview.chromium.org/1430953004/ (not landed yet):

severe: [InvalidFieldOverride] Field declaration
_ControllerSubscription<T>._controller cannot be overridden in
_BroadcastSubscription. (dart:async/broadcast_stream_controller.dart, line 40,
col 3)
==========

to

==========
Fix field override error

This fixes the following error reported by
https://codereview.chromium.org/1430953004/ (not landed yet):

severe: [InvalidFieldOverride] Field declaration
_ControllerSubscription<T>._controller cannot be overridden in
_BroadcastSubscription. (dart:async/broadcast_stream_controller.dart, line 40,
col 3)

Devon: this should address https://github.com/flutter/atom-flutter-dev/issues/2
==========

[vsm, 2015-11-06 15:12:58]

vsm@google.com changed reviewers:
+ devoncarew@google.com, jmesserly@google.com

[Leaf, 2015-11-06 22:11:18]

leafp@google.com changed reviewers:
+ leafp@google.com

[Leaf, 2015-11-06 22:11:19]

lgtm

[vsm, 2015-11-06 22:13:29]

Committed patchset #1 (id:1) manually as
927028ec663ba544ee39d8b137c88f0ea65285d5 (presubmit successful).