Add more tested features to closure_test

pkg/compiler/lib/src/js_model/closure.dart

Index: pkg/compiler/lib/src/js_model/closure.dart
diff --git a/pkg/compiler/lib/src/js_model/closure.dart b/pkg/compiler/lib/src/js_model/closure.dart
index 0436998eb87b3814a120a928be95c6d2ae56185d..1e086df0ee1e031e229e06446932c0be6b491f6b 100644
--- a/pkg/compiler/lib/src/js_model/closure.dart
+++ b/pkg/compiler/lib/src/js_model/closure.dart
@@ -182,10 +182,18 @@ class KernelClosureConversionTask extends ClosureConversionTask<ir.Node> {
   @override
   ClosureRepresentationInfo getClosureRepresentationInfo(Entity entity) {
     var closure = _closureRepresentationMap[entity];
-    assert(closure != null,
-        "Corresponding closure class not found for $entity. Closures found for ${_closureRepresentationMap.keys}");
+    assert(
+        closure != null,
+        "Corresponding closure class not found for $entity. "
+        "Closures found for ${_closureRepresentationMap.keys}");
     return closure;
   }
+
+  @override
+  ClosureRepresentationInfo getClosureRepresentationInfoForTesting(
+      Entity member) {
+    return _closureRepresentationMap[member];
+  }
 }
 
 class KernelScopeInfo {