Update dart:async to match the Dart repo.

tool/input_sdk/lib/async/stream_pipe.dart

Index: tool/input_sdk/lib/async/stream_pipe.dart
diff --git a/tool/input_sdk/lib/async/stream_pipe.dart b/tool/input_sdk/lib/async/stream_pipe.dart
index 3683719062d332df6676ca6cca5a0f7cf5ed5792..1125620aacb3b7b445c3745e8a079c725a980f37 100644
--- a/tool/input_sdk/lib/async/stream_pipe.dart
+++ b/tool/input_sdk/lib/async/stream_pipe.dart
@@ -47,10 +47,15 @@ void _cancelAndErrorWithReplacement(StreamSubscription subscription,
   _cancelAndError(subscription, future, error, stackTrace);
 }
 
+typedef void _ErrorCallback(error, StackTrace stackTrace);
+
 /** Helper function to make an onError argument to [_runUserCode]. */
-_cancelAndErrorClosure(StreamSubscription subscription, _Future future) =>
-  ((error, StackTrace stackTrace) => _cancelAndError(
-      subscription, future, error, stackTrace));
+_ErrorCallback _cancelAndErrorClosure(
+    StreamSubscription subscription, _Future future) {
+  return (error, StackTrace stackTrace) {
+    _cancelAndError(subscription, future, error, stackTrace);
+  };
+}
 
 /** Helper function to cancel a subscription and wait for the potential future,
   before completing with a value. */
@@ -100,8 +105,7 @@ abstract class _ForwardingStream<S, T> extends Stream<T> {
   // Override the following methods in subclasses to change the behavior.
 
   void _handleData(S data, _EventSink<T> sink) {
-    dynamic outputData = data;
-    sink._add(outputData);
+    sink._add(data as Object /*=T*/);
   }
 
   void _handleError(error, StackTrace stackTrace, _EventSink<T> sink) {
@@ -161,7 +165,7 @@ class _ForwardingStreamSubscription<S, T>
     if (_subscription != null) {
       StreamSubscription subscription = _subscription;
       _subscription = null;
-      subscription.cancel();
+      return subscription.cancel();
     }
     return null;
   }
@@ -224,7 +228,7 @@ typedef T _Transformation<S, T>(S value);
  * A stream pipe that converts data events before passing them on.
  */
 class _MapStream<S, T> extends _ForwardingStream<S, T> {
-  final _Transformation _transform;
+  final _Transformation<S, T> _transform;
 
   _MapStream(Stream<S> source, T transform(S event))
       : this._transform = transform, super(source);
@@ -308,20 +312,32 @@ class _HandleErrorStream<T> extends _ForwardingStream<T, T> {
 
 
 class _TakeStream<T> extends _ForwardingStream<T, T> {
-  int _remaining;
+  final int _count;
 
   _TakeStream(Stream<T> source, int count)
-      : this._remaining = count, super(source) {
+      : this._count = count, super(source) {
     // This test is done early to avoid handling an async error
     // in the _handleData method.
     if (count is! int) throw new ArgumentError(count);
   }
 
+  StreamSubscription<T> _createSubscription(
+      void onData(T data),
+      Function onError,
+      void onDone(),
+      bool cancelOnError) {
+    return new _StateStreamSubscription<T>(
+        this, onData, onError, onDone, cancelOnError, _count);
+  }
+
   void _handleData(T inputEvent, _EventSink<T> sink) {
-    if (_remaining > 0) {
+    _StateStreamSubscription<T> subscription = sink;
+    int count = subscription._count;
+    if (count > 0) {
       sink._add(inputEvent);
-      _remaining -= 1;
-      if (_remaining == 0) {
+      count -= 1;
+      subscription._count = count;
+      if (count == 0) {
         // Closing also unsubscribes all subscribers, which unsubscribes
         // this from source.
         sink._close();
@@ -330,6 +346,26 @@ class _TakeStream<T> extends _ForwardingStream<T, T> {
   }
 }
 
+/**
+ * A [_ForwardingStreamSubscription] with one extra state field.
+ *
+ * Use by several different classes, some storing an integer, others a bool.
+ */
+class _StateStreamSubscription<T> extends _ForwardingStreamSubscription<T, T> {
+  // Raw state field. Typed access provided by getters and setters below.
+  var _sharedState;
+
+  _StateStreamSubscription(_ForwardingStream<T, T> stream, void onData(T data),
+                           Function onError, void onDone(),
+                           bool cancelOnError, this._sharedState)
+      : super(stream, onData, onError, onDone, cancelOnError);
+
+  bool get _flag => _sharedState;
+  void set _flag(bool flag) { _sharedState = flag; }
+  int get _count => _sharedState;
+  void set _count(int count) { _sharedState = count; }
+}
+
 
 class _TakeWhileStream<T> extends _ForwardingStream<T, T> {
   final _Predicate<T> _test;
@@ -356,18 +392,29 @@ class _TakeWhileStream<T> extends _ForwardingStream<T, T> {
 }
 
 class _SkipStream<T> extends _ForwardingStream<T, T> {
-  int _remaining;
+  final int _count;
 
   _SkipStream(Stream<T> source, int count)
-      : this._remaining = count, super(source) {
+      : this._count = count, super(source) {
     // This test is done early to avoid handling an async error
     // in the _handleData method.
     if (count is! int || count < 0) throw new ArgumentError(count);
   }
 
+  StreamSubscription<T> _createSubscription(
+      void onData(T data),
+      Function onError,
+      void onDone(),
+      bool cancelOnError) {
+    return new _StateStreamSubscription<T>(
+        this, onData, onError, onDone, cancelOnError, _count);
+  }
+
   void _handleData(T inputEvent, _EventSink<T> sink) {
-    if (_remaining > 0) {
-      _remaining--;
+    _StateStreamSubscription<T> subscription = sink;
+    int count = subscription._count;
+    if (count > 0) {
+      subscription._count = count - 1;
       return;
     }
     sink._add(inputEvent);
@@ -376,13 +423,23 @@ class _SkipStream<T> extends _ForwardingStream<T, T> {
 
 class _SkipWhileStream<T> extends _ForwardingStream<T, T> {
   final _Predicate<T> _test;
-  bool _hasFailed = false;
 
   _SkipWhileStream(Stream<T> source, bool test(T value))
       : this._test = test, super(source);
 
+  StreamSubscription<T> _createSubscription(
+      void onData(T data),
+      Function onError,
+      void onDone(),
+      bool cancelOnError) {
+    return new _StateStreamSubscription<T>(
+        this, onData, onError, onDone, cancelOnError, false);
+  }
+
   void _handleData(T inputEvent, _EventSink<T> sink) {
-    if (_hasFailed) {
+    _StateStreamSubscription<T> subscription = sink;
+    bool hasFailed = subscription._flag;
+    if (hasFailed) {
       sink._add(inputEvent);
       return;
     }
@@ -392,11 +449,11 @@ class _SkipWhileStream<T> extends _ForwardingStream<T, T> {
     } catch (e, s) {
       _addErrorWithReplacement(sink, e, s);
       // A failure to return a boolean is considered "not matching".
-      _hasFailed = true;
+      subscription._flag = true;
       return;
     }
     if (!satisfies) {
-      _hasFailed = true;
+      subscription._flag = true;
       sink._add(inputEvent);
     }
   }
@@ -423,7 +480,7 @@ class _DistinctStream<T> extends _ForwardingStream<T, T> {
         if (_equals == null) {
           isEqual = (_previous == inputEvent);
         } else {
-          isEqual = _equals(_previous, inputEvent);
+          isEqual = _equals(_previous as Object /*=T*/, inputEvent);
         }
       } catch (e, s) {
         _addErrorWithReplacement(sink, e, s);