Re-enable kernel unit tests on platforms where they are supported.

pkg/pkg.status

Index: pkg/pkg.status
diff --git a/pkg/pkg.status b/pkg/pkg.status
index 277865a7c8ac3ed20f5022e0a724ebf4d53b66ac..a4a5ef4ba77e8843f5560e4bd438d0380c4b8a70 100644
--- a/pkg/pkg.status
+++ b/pkg/pkg.status
@@ -120,6 +120,9 @@ observe/test/transformer_test: Fail, OK # Uses dart:io.
 observe/test/unique_message_test: SkipByDesign  # Uses dart:io.
 dart_messages/test/dart_messages_test: Skip  # Uses dart:io.
 
+[ $browser || $jscl ]
+kernel/test/*: SkipByDesign # Uses dart:io and bigints.
+
 [ $runtime == vm && ($arch == simarm64 || $arch == simarm || $arch == simarmv6 || $arch == simarmv5te || $arch == simmips || $arch == armv6 || $arch == armv5te) ]
 # Timeout. These are not unit tests. They do not run efficiently on our
 # simulator or low-end devices.