Only use white list on indefinite checks

tool/input_sdk/private/ddc_runtime/operations.dart

Index: tool/input_sdk/private/ddc_runtime/operations.dart
diff --git a/tool/input_sdk/private/ddc_runtime/operations.dart b/tool/input_sdk/private/ddc_runtime/operations.dart
index 3ec38119608e5a59a3b5f3b22a6111fe2b4d51b3..97359b68e263c0fb5b73c9a93407d39f31b294e6 100644
--- a/tool/input_sdk/private/ddc_runtime/operations.dart
+++ b/tool/input_sdk/private/ddc_runtime/operations.dart
@@ -204,6 +204,7 @@ strongInstanceOf(obj, type, ignoreFromWhiteList) => JS('', '''(() => {
   let result = $isSubtype(actual, $type);
   if (result || actual == $jsobject ||
       actual == $int && type == $double) return true;
+  if (result === false) return false;
   if ($ignoreFromWhiteList == void 0) return result;
   if ($_ignoreTypeFailure(actual, $type)) return true;
   return result;