Assert that we don't mix K and J elements

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 0bcda3d2f569bb97fcf3e3843ba534b6c40486db..8bb9bba458b70e0986582e4785eb75e3f17df3e6 100644
--- a/pkg/compiler/lib/src/kernel/native_basic_data.dart
+++ b/pkg/compiler/lib/src/kernel/native_basic_data.dart
@@ -7,11 +7,11 @@ part of dart2js.kernel.element_map;
 
 class KernelAnnotationProcessor implements AnnotationProcessor {
   final KernelToElementMapForImpactImpl2 elementMap;
+  final NativeBasicDataBuilder _nativeBasicDataBuilder;
 
-  KernelAnnotationProcessor(this.elementMap);
+  KernelAnnotationProcessor(this.elementMap, this._nativeBasicDataBuilder);
 
-  void extractNativeAnnotations(
-      LibraryEntity library, NativeBasicDataBuilder nativeBasicDataBuilder) {
+  void extractNativeAnnotations(LibraryEntity library) {
     ElementEnvironment elementEnvironment = elementMap.elementEnvironment;
     CommonElements commonElements = elementMap.commonElements;
 
@@ -30,13 +30,14 @@ class KernelAnnotationProcessor implements AnnotationProcessor {
         }
       }
       if (annotationName != null) {
-        nativeBasicDataBuilder.setNativeClassTagInfo(cls, annotationName);
+        _nativeBasicDataBuilder.setNativeClassTagInfo(cls, annotationName);
       }
     });
   }
 
   void extractJsInteropAnnotations(
-      LibraryEntity library, NativeBasicDataBuilder nativeBasicDataBuilder) {
+    LibraryEntity library,

[Siggi Cherem (dart-lang), 2017/07/06 18:14:00]

nit: delete trailing `,`

[Johnni Winther, 2017/07/07 09:58:28]

Done.

+  ) {
     // TODO(redemption): Implement this.
   }