Revert "added  ignore: uri_does_not_exist workaround for conditional imports and old analyzer bug."

This reverts commit 431aa4a2dfc163731791d114d0d9d1b50672fcc5.
diff --git a/lib/src/sha512.dart b/lib/src/sha512.dart
index bbea817..45a4ac2 100644
--- a/lib/src/sha512.dart
+++ b/lib/src/sha512.dart
@@ -6,9 +6,6 @@
 
 import 'digest.dart';
 import 'hash.dart';
-// The below comment is a workaround for an old analyzer error. It goes away
-// with ddk.
-// ignore: uri_does_not_exist
 import 'sha512_fastsinks.dart' if (dart.library.js) 'sha512_slowsinks.dart';
 //import 'sha512_slowsinks.dart';
 import 'utils.dart';