Fix runtime cast failure in chainForTrace(). See: https://github.com/dart-lang/sdk/issues/27223

diff --git a/pkgs/stack_trace/CHANGELOG.md b/pkgs/stack_trace/CHANGELOG.md
index 2627e71..3c6e56c 100644
--- a/pkgs/stack_trace/CHANGELOG.md
+++ b/pkgs/stack_trace/CHANGELOG.md

@@ -1,4 +1,9 @@
+## 1.9.1+1
+
+* Fix Dart 2.0 runtime cast failure in test.
+
 ## 1.9.1
+
 * Preserve the original chain for a trace to handle cases where an
   error is rethrown.
 

diff --git a/pkgs/stack_trace/pubspec.yaml b/pkgs/stack_trace/pubspec.yaml
index f7c562d..93ffeb3 100644
--- a/pkgs/stack_trace/pubspec.yaml
+++ b/pkgs/stack_trace/pubspec.yaml

@@ -7,7 +7,7 @@
 #
 # When the major version is upgraded, you *must* update that version constraint
 # in pub to stay in sync with this.
-version: 1.9.1
+version: 1.9.1+1
 author: "Dart Team <misc@dartlang.org>"
 homepage: https://github.com/dart-lang/stack_trace
 description: A package for manipulating stack traces and printing them readably.

diff --git a/pkgs/stack_trace/test/chain/utils.dart b/pkgs/stack_trace/test/chain/utils.dart
index bf82158..0c5c983 100644
--- a/pkgs/stack_trace/test/chain/utils.dart
+++ b/pkgs/stack_trace/test/chain/utils.dart

@@ -64,7 +64,7 @@
 /// Runs [callback] within [asyncFn], then converts any errors raised into a
 /// [Chain] with [Chain.forTrace].
 Future<Chain> chainForTrace(asyncFn(callback()), callback()) {
-  var completer = new Completer();
+  var completer = new Completer<Chain>();
   asyncFn(() {
     // We use `new Future.value().then(...)` here as opposed to [new Future] or
     // [new Future.sync] because those methods don't pass the exception through
@@ -75,10 +75,8 @@
         .catchError(completer.completeError);
   });
 
-  // TODO(rnystrom): Remove this cast if catchError() gets a better type.
   return completer.future
-          .catchError((_, stackTrace) => new Chain.forTrace(stackTrace))
-      as Future<Chain>;
+      .catchError((_, stackTrace) => new Chain.forTrace(stackTrace));
 }
 
 /// Runs [callback] in a [Chain.capture] zone and returns a Future that