Add ClosureRepresentationInfo, the new public face of ClosureClassMap

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 4b8ff757640eeb5e6cc7b27f6c68e84a286177da..fcea437f3a769ecc66f9eab47d22820bcfd4ab9e 100644
--- a/pkg/compiler/lib/src/kernel/kernel_backend_strategy.dart
+++ b/pkg/compiler/lib/src/kernel/kernel_backend_strategy.dart
@@ -331,6 +331,11 @@ class KernelClosureClassMaps implements ClosureClassMaps<ir.Node> {
       ir.Node loopNode) {
     return const LoopClosureRepresentationInfo();
   }
+
+  @override
+  ClosureRepresentationInfo getClosureRepresentationInfo(Entity entity) {
+    return const ClosureRepresentationInfo();
+  }
 }
 
 class KernelSorter implements Sorter {