More strong mode clean-up

pkg/analyzer/lib/src/cancelable_future.dart

Index: pkg/analyzer/lib/src/cancelable_future.dart
diff --git a/pkg/analyzer/lib/src/cancelable_future.dart b/pkg/analyzer/lib/src/cancelable_future.dart
index 803137d1beb47f501ffe7bb8c073ec05b5bbfbd6..307e1d9a8962d4678e2f5c0c7874a950ba7b7f0a 100644
--- a/pkg/analyzer/lib/src/cancelable_future.dart
+++ b/pkg/analyzer/lib/src/cancelable_future.dart
@@ -248,7 +248,7 @@ class _CancelableCompleterFuture<T> implements CancelableFuture<T> {
   }
 
   @override
-  Future catchError(Function onError, {bool test(Object error)}) =>
+  Future<T> catchError(Function onError, {bool test(Object error)}) =>
       _completer._outerCompleter.future.catchError(onError, test: test);
 
   @override
@@ -284,7 +284,7 @@ class _WrappedFuture<T> implements CancelableFuture<T> {
   void cancel() {}
 
   @override
-  Future catchError(Function onError, {bool test(Object error)}) =>
+  Future<T> catchError(Function onError, {bool test(Object error)}) =>
       _future.catchError(onError, test: test);
 
   @override