Fix typo in native_helper and add dartc test.

lib/compiler/implementation/lib/native_helper.dart

Index: lib/compiler/implementation/lib/native_helper.dart
diff --git a/lib/compiler/implementation/lib/native_helper.dart b/lib/compiler/implementation/lib/native_helper.dart
index fd0a652ba56af5b674ce972079186fc0f011db37..366fd32f413192bd671184bf48aa9ec0b63cb60f 100644
--- a/lib/compiler/implementation/lib/native_helper.dart
+++ b/lib/compiler/implementation/lib/native_helper.dart
@@ -232,7 +232,7 @@ List<MetaInfo> get _dynamicMetadata() {
   return JS('var', '\$dynamicMetadata');
 }
 
-void set _dynamicMetadata(List<String> table) {
+void set _dynamicMetadata(List<MetaInfo> table) {
   JS('void', '\$dynamicMetadata = #', table);
 }