Revert "Revert "Use native async/await support in pub.""

sdk/lib/_internal/pub_generated/lib/src/transcript.dart

Index: sdk/lib/_internal/pub_generated/lib/src/transcript.dart
diff --git a/sdk/lib/_internal/pub_generated/lib/src/transcript.dart b/sdk/lib/_internal/pub_generated/lib/src/transcript.dart
deleted file mode 100644
index a2778c0c824a63236cd89258917885a961e988d4..0000000000000000000000000000000000000000
--- a/sdk/lib/_internal/pub_generated/lib/src/transcript.dart
+++ /dev/null
@@ -1,73 +0,0 @@
-// Copyright (c) 2012, 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.
-
-library pub.transcript;
-
-import 'dart:collection';
-
-/// A rolling transcript of entries of type [T].
-///
-/// It has a maximum number of entries. If entries are added that exceed that
-/// it discards entries from the *middle* of the transcript. Generally, in logs,
-/// the first and last entries are the most important, so it maintains those.
-class Transcript<T> {
-  /// The maximum number of transcript entries.
-  final int max;
-
-  /// The number of entries that were discarded after reaching [max].
-  int get discarded => _discarded;
-  int _discarded = 0;
-
-  /// The earliest half of the entries.
-  ///
-  /// This will be empty until the maximum number of entries is hit at which
-  /// point the oldest half of the entries will be moved from [_newest] to
-  /// here.
-  final _oldest = new List<T>();
-
-  /// The most recent half of the entries.
-  final _newest = new Queue<T>();
-
-  /// Creates a new [Transcript] that can hold up to [max] entries.
-  Transcript(this.max);
-
-  /// Adds [entry] to the transcript.
-  ///
-  /// If the transcript already has the maximum number of entries, discards one
-  /// from the middle.
-  void add(T entry) {
-    if (discarded > 0) {
-      // We're already in "rolling" mode.
-      _newest.removeFirst();
-      _discarded++;
-    } else if (_newest.length == max) {
-      // We are crossing the threshold where we have to discard items. Copy
-      // the first half over to the oldest list.
-      while (_newest.length > max ~/ 2) {
-        _oldest.add(_newest.removeFirst());
-      }
-
-      // Discard the middle item.
-      _newest.removeFirst();
-      _discarded++;
-    }
-
-    _newest.add(entry);
-  }
-
-  /// Traverses the entries in the transcript from oldest to newest.
-  ///
-  /// Invokes [onEntry] for each item. When it reaches the point in the middle
-  /// where excess entries where dropped, invokes [onGap] with the number of
-  /// dropped entries. If no more than [max] entries were added, does not
-  /// invoke [onGap].
-  void forEach(void onEntry(T entry), [void onGap(int)]) {
-    if (_oldest.isNotEmpty) {
-      _oldest.forEach(onEntry);
-      if (onGap != null) onGap(discarded);
-    }
-
-    _newest.forEach(onEntry);
-  }
-}