Mostly use Entity in InterceptorData

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

Index: pkg/compiler/lib/src/kernel/world_builder.dart
diff --git a/pkg/compiler/lib/src/kernel/world_builder.dart b/pkg/compiler/lib/src/kernel/world_builder.dart
index 758687d64031c8f1f5ccc3d4c7182ba1b86a7d3e..615384888785c5d9e46be242ae4745625ef94186 100644
--- a/pkg/compiler/lib/src/kernel/world_builder.dart
+++ b/pkg/compiler/lib/src/kernel/world_builder.dart
@@ -565,6 +565,18 @@ class KernelElementEnvironment implements ElementEnvironment {
   }
 
   @override
+  void forEachMixin(ClassEntity cls, void f(ClassEntity mixin)) {
+    throw new UnimplementedError('KernelElementEnvironment.forEachMixin');
+  }
+
+  @override
+  void forEachClassMember(
+      ClassEntity cls, void f(ClassEntity declarer, MemberEntity member)) {
+    throw new UnimplementedError(
+        'KernelElementEnvironment.forEachInstanceMember');
+  }
+
+  @override
   MemberEntity lookupLibraryMember(LibraryEntity library, String name,
       {bool setter: false, bool required: false}) {
     MemberEntity member =