Handle const Symbol(...) in kernel_impact

pkg/compiler/lib/src/kernel/native_basic_data.dart

Index: pkg/compiler/lib/src/kernel/native_basic_data.dart
diff --git a/pkg/compiler/lib/src/kernel/native_basic_data.dart b/pkg/compiler/lib/src/kernel/native_basic_data.dart
index 36364c4d24dcef8ac8bc36f1118a447b06873ecd..23db2230606dbf6c0cec6df8d1dbbbcc9eb24f34 100644
--- a/pkg/compiler/lib/src/kernel/native_basic_data.dart
+++ b/pkg/compiler/lib/src/kernel/native_basic_data.dart
@@ -19,9 +19,7 @@ class KernelAnnotationProcessor implements AnnotationProcessor {
       String annotationName;
       // TODO(johnniwinther): Make [_getClassMetadata] public and at test to
       // guard against misuse.
-      for (ConstantExpression annotation in elementMap._getClassMetadata(cls)) {
-        ConstantValue value =
-            elementMap.constantEnvironment.getConstantValue(annotation);
+      for (ConstantValue value in elementMap._getClassMetadata(cls)) {
         String name = readAnnotationName(
             cls, value, commonElements.nativeAnnotationClass);
         if (annotationName == null) {