Revert "Revert "Make stdout/stderr async""

sdk/lib/io/stdio.dart

Index: sdk/lib/io/stdio.dart
diff --git a/sdk/lib/io/stdio.dart b/sdk/lib/io/stdio.dart
index 9888d9516887274093a83634259ef1b50f627802..e4bdf01ff05c7bb0b6d68ba8c53d1a743d319d0c 100644
--- a/sdk/lib/io/stdio.dart
+++ b/sdk/lib/io/stdio.dart
@@ -149,29 +149,17 @@ class Stdin extends _StdStream implements Stream<List<int>> {
 
 
 /**
- * [Stdout] represents the [IOSink] for either `stdout` or `stderr`.
+ * [Stdout] exposes methods to query the terminal for properties.
  *
- * It provides a *blocking* `IOSink`, so using this to write will block until
- * the output is written.
- *
- * In some situations this blocking behavior is undesirable as it does not
- * provide the same non-blocking behavior as dart:io in general exposes.
- * Use the property [nonBlocking] to get an `IOSink` which has the non-blocking
- * behavior.
- *
- * This class can also be used to check whether `stdout` or `stderr` is
- * connected to a terminal and query some terminal properties.
+ * Use [hasTerminal] to test if there is a terminal associated to stdout.
  */
 class Stdout extends _StdSink implements IOSink {
-  final int _fd;
-  IOSink _nonBlocking;
-
-  Stdout._(IOSink sink, this._fd) : super(sink);
+  Stdout._(IOSink sink) : super(sink);
 
   /**
    * Returns true if there is a terminal attached to stdout.
    */
-  bool get hasTerminal => _hasTerminal(_fd);
+  external bool get hasTerminal;
 
   /**
    * Get the number of columns of the terminal.
@@ -179,7 +167,7 @@ class Stdout extends _StdSink implements IOSink {
    * If no terminal is attached to stdout, a [StdoutException] is thrown. See
    * [hasTerminal] for more info.
    */
-  int get terminalColumns => _terminalColumns(_fd);
+  external int get terminalColumns;
 
   /**
    * Get the number of lines of the terminal.
@@ -187,21 +175,7 @@ class Stdout extends _StdSink implements IOSink {
    * If no terminal is attached to stdout, a [StdoutException] is thrown. See
    * [hasTerminal] for more info.
    */
-  int get terminalLines => _terminalLines(_fd);
-
-  external bool _hasTerminal(int fd);
-  external int _terminalColumns(int fd);
-  external int _terminalLines(int fd);
-
-  /**
-   * Get a non-blocking `IOSink`.
-   */
-  IOSink get nonBlocking {
-    if (_nonBlocking == null) {
-      _nonBlocking = new IOSink(new _FileStreamConsumer.fromStdio(_fd));
-    }
-    return _nonBlocking;
-  }
+  external int get terminalLines;
 }
 
 
@@ -216,34 +190,6 @@ class StdoutException implements IOException {
   }
 }
 
-class _StdConsumer implements StreamConsumer<List<int>> {
-  final _file;
-
-  _StdConsumer(int fd) : _file = _File._openStdioSync(fd);
-
-  Future addStream(Stream<List<int>> stream) {
-    var completer = new Completer();
-    var sub;
-    sub = stream.listen(
-        (data) {
-          try {
-            _file.writeFromSync(data);
-          } catch (e, s) {
-            sub.cancel();
-            completer.completeError(e, s);
-          }
-        },
-        onError: completer.completeError,
-        onDone: completer.complete,
-        cancelOnError: true);
-    return completer.future;
-  }
-
-  Future close() {
-    _file.closeSync();
-    return new Future.value();
-  }
-}
 
 class _StdSink implements IOSink {
   final IOSink _sink;
@@ -281,7 +227,7 @@ class StdioType {
 
 Stdin _stdin;
 Stdout _stdout;
-Stdout _stderr;
+IOSink _stderr;
 
 
 /// The standard input stream of data read by this program.
@@ -303,7 +249,7 @@ Stdout get stdout {
 
 
 /// The standard output stream of errors written by this program.
-Stdout get stderr {
+IOSink get stderr {
   if (_stderr == null) {
     _stderr = _StdIOUtils._getStdioOutputStream(2);
   }