Remove deprecated parts of dart:async.

sdk/lib/_internal/pub/lib/src/solver/backtracking_solver.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.
 
 /// A back-tracking depth-first solver. Attempts to find the best solution for
 /// a root package's transitive dependency graph, where a "solution" is a set
 /// of concrete package versions. A valid solution will select concrete
 /// versions for every package reached from the root package's dependency graph,
 /// and each of those packages will fit the version constraints placed on it.
 ///
@@ skipping 386 matching lines @@
       // Given a package dep, returns a future that completes to a pair of the
       // dep and the number of versions available for it.
       getNumVersions(PackageDep dep) {
         // There is only ever one version of the root package.
         if (dep.isRoot) {
           return new Future.value(new Pair<PackageDep, int>(dep, 1));
         }
 
         return _solver.cache.getVersions(dep.toRef()).then((versions) {
           return new Pair<PackageDep, int>(dep, versions.length);
-        }).catchError((error) {
+        }).catchError((error, trace) {
           // If it fails for any reason, just treat that as no versions. This
           // will sort this reference higher so that we can traverse into it
           // and report the error more properly.
-          log.solver("Could not get versions for $dep:\n$error\n\n"
-              "${getAttachedStackTrace(error)}");
+          log.solver("Could not get versions for $dep:\n$error\n\n$trace");
           return new Pair<PackageDep, int>(dep, 0);
         });
       }
 
       return Future.wait(deps.map(getNumVersions)).then((pairs) {
         // Future.wait() returns an immutable list, so make a copy.
         pairs = pairs.toList();
 
         // Sort in best-first order to minimize backtracking.
         pairs.sort((a, b) {
@@ skipping 213 matching lines @@
   // know what they're doing.
   if (sdk.isBleedingEdge) return;
 
   if (pubspec.environment.sdkVersion.allows(sdk.version)) return;
 
   throw new BadSdkVersionException(pubspec.name,
       'Package ${pubspec.name} requires SDK version '
       '${pubspec.environment.sdkVersion} but the current SDK is '
       '${sdk.version}.');
 }