Add type info to fix analyzer failures for 1.23.0-dev.5.0

lib/src/runner/loader.dart

Index: lib/src/runner/loader.dart
diff --git a/lib/src/runner/loader.dart b/lib/src/runner/loader.dart
index f24ddd0dd3b7b71ba284708b303077875966e812..3fa735a5c207a98325a6954a42b6640d769e5043 100644
--- a/lib/src/runner/loader.dart
+++ b/lib/src/runner/loader.dart
@@ -164,7 +164,8 @@ class Loader {
           return suite;
         } catch (error, stackTrace) {
           if (error is LoadException) rethrow;
-          await new Future.error(new LoadException(path, error), stackTrace);
+          await new Future<RunnerSuite>.error(
+              new LoadException(path, error), stackTrace);

[nweiz, 2017/03/10 21:24:34]

I think it would be cleaner to just add "return null" after this.

[keertip, 2017/03/10 21:30:37]

Done.

         }
       }, path: path, platform: platform);
     }