Roll to pickup pool changes

packages/stack_trace/lib/src/chain.dart

Index: packages/stack_trace/lib/src/chain.dart
diff --git a/packages/stack_trace/lib/src/chain.dart b/packages/stack_trace/lib/src/chain.dart
index 2d1349de2076f0b9dc685b9274dbe8bfc3935a66..01bf06fb7df0790d7c9d3318e974ff975cf44fbc 100644
--- a/packages/stack_trace/lib/src/chain.dart
+++ b/packages/stack_trace/lib/src/chain.dart
@@ -93,7 +93,8 @@ class Chain implements StackTrace {
         return callback();
       } catch (error, stackTrace) {
         // TODO(nweiz): Don't special-case this when issue 19566 is fixed.
-        return Zone.current.handleUncaughtError(error, stackTrace);
+        Zone.current.handleUncaughtError(error, stackTrace);
+        return null;
       }
     },
         zoneSpecification: spec.toSpec(),
@@ -104,7 +105,7 @@ class Chain implements StackTrace {
   /// [callback] in a [Zone] in which chain capturing is disabled.
   ///
   /// If [callback] returns a value, it will be returned by [disable] as well.
-  static/*=T*/ disable/*<T>*/(/*=T*/ callback(), {bool when: true}) {
+  static T disable<T>(T callback(), {bool when: true}) {
     var zoneValues =
         when ? {_specKey: null, StackZoneSpecification.disableKey: true} : null;