Remove deprecated parts of dart:async.

sdk/lib/async/async_error.dart

 // 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.
 
 part of dart.async;
 
-final Expando _stackTraceExpando = new Expando("asynchronous error");
-
-void _attachStackTrace(o, StackTrace st) {
-  if (o == null || o is bool || o is num || o is String) return;
-  _stackTraceExpando[o] = st;
-}
-
 _invokeErrorHandler(Function errorHandler,
                     Object error, StackTrace stackTrace) {
   if (errorHandler is ZoneBinaryCallback) {
     return errorHandler(error, stackTrace);
   } else {
     return errorHandler(error);
   }
 }
 
 Function _registerErrorHandler(Function errorHandler, Zone zone) {
   if (errorHandler is ZoneBinaryCallback) {
     return zone.registerBinaryCallback(errorHandler);
   } else {
     return zone.registerUnaryCallback(errorHandler);
   }
 }
 
-/**
- * *DEPRECATED*. Use explicit stack trace arguments instead.
- *
- * Get the [StackTrace] attached to [o].
- *
- * If object [o] was thrown and caught in a dart:async method, a [StackTrace]
- * object was attached to it. Use [getAttachedStackTrace] to get that object.
- *
- * Returns [null] if no [StackTrace] was attached.
- */
-@deprecated
-getAttachedStackTrace(o) {
-  if (o == null || o is bool || o is num || o is String) return null;
-  return _stackTraceExpando[o];
-}
-
 class _AsyncError implements Error {
   final error;
   final StackTrace stackTrace;
 
   _AsyncError(this.error, this.stackTrace);
 }
 
 class _UncaughtAsyncError extends _AsyncError {
   _UncaughtAsyncError(error, StackTrace stackTrace)
-      : super(error, _getBestStackTrace(error, stackTrace)) {
-    // Clear the attached stack trace.
-    _attachStackTrace(error, null);
-  }
+      : super(error, _getBestStackTrace(error, stackTrace));
 
   static StackTrace _getBestStackTrace(error, StackTrace stackTrace) {
     if (stackTrace != null) return stackTrace;
-    var trace = getAttachedStackTrace(error);
-    if (trace != null) return trace;
     if (error is Error) {
-      Error e = error;
-      return e.stackTrace;
+      return error.stackTrace;
     }
     return null;
   }
 
   String toString() {
     String result = "Uncaught Error: ${error}";
 
     if (stackTrace != null) {
       result += "\nStack Trace:\n$stackTrace";
     }
     return result;
   }
 }