Create new interface instead of ClosureClassMap for variable usage information that is not Element-…

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

Index: pkg/compiler/lib/src/kernel/kernel_backend_strategy.dart
diff --git a/pkg/compiler/lib/src/kernel/kernel_backend_strategy.dart b/pkg/compiler/lib/src/kernel/kernel_backend_strategy.dart
index 0c05879dda17ebe647d458a2d034ac16ed2fc4ae..dad6f8094a8853e37f7f5ce23cef0fe54eae8d02 100644
--- a/pkg/compiler/lib/src/kernel/kernel_backend_strategy.dart
+++ b/pkg/compiler/lib/src/kernel/kernel_backend_strategy.dart
@@ -216,6 +216,9 @@ class KernelToTypeInferenceMapImpl implements KernelToTypeInferenceMap {
 class KernelClosureClassMaps implements ClosureClassMaps {
   const KernelClosureClassMaps();
 
+  // TODO(efortuna);
+  ClassEntity getClosureClassEntity(Local member);

[Johnni Winther, 2017/05/31 12:39:51]

Add a `=> null;` body to avoid warnings.

+
   @override
   ClosureClassMap getLocalFunctionMap(Local localFunction) {
     return new ClosureClassMap(null, null, null, null);