Use more entities in program_builder, collector and registry

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

Index: pkg/compiler/lib/src/js_backend/runtime_types.dart
diff --git a/pkg/compiler/lib/src/js_backend/runtime_types.dart b/pkg/compiler/lib/src/js_backend/runtime_types.dart
index 9482a9e3391a59fbebbd1f51fd9a78e773f9dcb1..f6a5ffe625523dd6f134391efe0503d60ab23d56 100644
--- a/pkg/compiler/lib/src/js_backend/runtime_types.dart
+++ b/pkg/compiler/lib/src/js_backend/runtime_types.dart
@@ -455,7 +455,7 @@ class _RuntimeTypes extends _RuntimeTypesBase
 
   @override
   TypeChecks computeChecks(
-      Set<ClassElement> instantiated, Set<ClassElement> checked) {
+      Set<ClassEntity> instantiated, Set<ClassEntity> checked) {
     // Run through the combination of instantiated and checked
     // arguments and record all combination where the element of a checked
     // argument is a superclass of the element of an instantiated type.