Use entities in BackendClasses

pkg/compiler/lib/src/js_backend/lookup_map_analysis.dart

Index: pkg/compiler/lib/src/js_backend/lookup_map_analysis.dart
diff --git a/pkg/compiler/lib/src/js_backend/lookup_map_analysis.dart b/pkg/compiler/lib/src/js_backend/lookup_map_analysis.dart
index eb9aa3ccea292b929168877db94e35edb60cf059..f3bb84e993c944d3c9e848af8f9b76b05c413b3a 100644
--- a/pkg/compiler/lib/src/js_backend/lookup_map_analysis.dart
+++ b/pkg/compiler/lib/src/js_backend/lookup_map_analysis.dart
@@ -285,8 +285,7 @@ class LookupMapAnalysis {
         // type_lookup_map/generic_type_test
         // TODO(sigmund): can we get rid of this?
         backend.computeImpactForInstantiatedConstantType(
-            backend.backendClasses.typeImplementation.rawType,
-            impactBuilderForCodegen);
+            backend.backendClasses.typeType, impactBuilderForCodegen);
         _addGenerics(arg);
       }
     }