[deps] roll package:lints to the latest

Change-Id: I582f956cd4b712203c2f6dd630b4e1384040446d
Tested: analysis clean (this is a lint only related change)
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/329400
Reviewed-by: Phil Quitslund <pquitslund@google.com>
Reviewed-by: Samuel Rawlins <srawlins@google.com>
Commit-Queue: Devon Carew <devoncarew@google.com>

pkg/js_shared/pubspec.yaml

@@ -3,7 +3,7 @@ name: js_shared
 publish_to: none
 
 environment:
-  sdk: '>=2.14.0 <3.0.0'
+  sdk: '>=2.19.0 <3.0.0'
 
 # Use 'any' constraints here; we get our versions from the DEPS file.
 dev_dependencies:

pkg/js_shared/test/in_sync_test.dart

@@ -3,6 +3,8 @@
 // BSD-style license that can be found in the LICENSE file.
 
 /// Test to verify that this package is in-sync with shared runtime libraries.
+library;
+
 import 'dart:io';
 
 import 'package:_fe_analyzer_shared/src/util/relativize.dart';