Remove some additional Chain.track documentation.

pkg/stack_trace/lib/src/stack_zone_specification.dart

 // Copyright (c) 2013, 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 stack_trace.stack_zone_specification;
 
 import 'dart:async';
 
 import 'trace.dart';
 import 'chain.dart';
 
 /// A class encapsulating the zone specification for a [Chain.capture] zone.
 ///
 /// Until they're materialized and exposed to the user, stack chains are tracked
 /// as linked lists of [Trace]s using the [_Node] class. These nodes are stored
 /// in three distinct ways:
 ///
 /// * When a callback is registered, a node is created and stored as a captured
 ///   local variable until the callback is run.
 ///
 /// * When a callback is run, its captured node is set as the [_currentNode] so
 ///   it can be available to [Chain.current] and to be linked into additional
 ///   chains when more callbacks are scheduled.
 ///
-/// * When a callback throws an error or a [Chain.track]ed Future or Stream
-///   emits an error, the current node is associated with that error's stack
-///   trace using the [_chains] expando.
+/// * When a callback throws an error or a Future or Stream emits an error, the
+///   current node is associated with that error's stack trace using the
+///   [_chains] expando.
 ///
 /// Since [ZoneSpecification] can't be extended or even implemented, in order to
 /// get a real [ZoneSpecification] instance it's necessary to call [toSpec].
 class StackZoneSpecification {
   /// The expando that associates stack chains with [StackTrace]s.
   ///
   /// The chains are associated with stack traces rather than errors themselves
   /// because it's a common practice to throw strings as errors, which can't be
   /// used with expandos.
   ///
@@ skipping 194 matching lines @@
   Chain toChain() {
     var nodes = <Trace>[];
     var node = this;
     while (node != null) {
       nodes.add(node.trace);
       node = node.previous;
     }
     return new Chain(nodes);
   }
 }