Remove deprecated parts of dart:async.

sdk/lib/_internal/pub/lib/src/command.dart

Index: sdk/lib/_internal/pub/lib/src/command.dart
diff --git a/sdk/lib/_internal/pub/lib/src/command.dart b/sdk/lib/_internal/pub/lib/src/command.dart
index 167e2d112fa346da809066e55b91286176c512a2..c6e25ead386e09395f4147ec529ea8ed8c3a1be0 100644
--- a/sdk/lib/_internal/pub/lib/src/command.dart
+++ b/sdk/lib/_internal/pub/lib/src/command.dart
@@ -88,9 +88,7 @@ abstract class PubCommand {
 
     cache = new SystemCache.withSources(cacheDir, isOffline: isOffline);
 
-    handleError(error) {
-      var trace = getAttachedStackTrace(error);
-
+    handleError(error, trace) {
       // This is basically the top-level exception handler so that we don't
       // spew a stack trace on our users.
       var message;