Assert that we don't mix K and J elements

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

 // Copyright (c) 2017, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library dart2js.js_model.elements;
 
 import '../common_elements.dart';
 import '../constants/constant_system.dart';
 import '../elements/elements.dart';
 import '../elements/entities.dart';
 import '../elements/names.dart';
 import '../elements/types.dart';
 import '../js_backend/backend_usage.dart';
 import '../js_backend/interceptor_data.dart';
 import '../js_backend/native_data.dart';
+import '../js_backend/runtime_types.dart';
 import '../kernel/elements.dart';
 import '../kernel/element_map_impl.dart';
 import '../native/behavior.dart';
 import '../universe/class_set.dart';
 import '../world.dart';
 
 /// Bidirectional map between 'frontend' and 'backend' elements.
 ///
 /// Frontend elements are what we read in, these typically represents concepts
 /// in Dart. Backend elements are what we generate, these may include elements
@@ skipping 226 matching lines @@
       TypeVariableType type, EntityConverter converter) {
     return new TypeVariableType(converter(type.element));
   }
 
   @override
   DartType visitVoidType(VoidType type, EntityConverter converter) {
     return const VoidType();
   }
 }
 
-const String jsElementPrefix = 'j';
+const String jsElementPrefix = 'j:';
 
 class JLibrary implements LibraryEntity, IndexedLibrary {
   /// Library index used for fast lookup in [JsToFrontendMapImpl].
   final int libraryIndex;
   final String name;
   final Uri canonicalUri;
 
   JLibrary(this.libraryIndex, this.name, this.canonicalUri);
 
   String toString() => '${jsElementPrefix}library($name)';
@@ skipping 213 matching lines @@
 
   JTypeVariable(
       this.typeVariableIndex, this.typeDeclaration, this.name, this.index);
 
   String toString() =>
       '${jsElementPrefix}type_variable(${typeDeclaration.name}.$name)';
 }
 
 class JsClosedWorld extends ClosedWorldBase with KernelClosedWorldMixin {
   final JsKernelToElementMap elementMap;
+  final RuntimeTypesNeed rtiNeed;
 
   JsClosedWorld(this.elementMap,
       {ElementEnvironment elementEnvironment,
       DartTypes dartTypes,
       CommonElements commonElements,
       ConstantSystem constantSystem,
       NativeData nativeData,
       InterceptorData interceptorData,
       BackendUsage backendUsage,
+      this.rtiNeed,
       Set<ClassEntity> implementedClasses,
+      Iterable<ClassEntity> liveNativeClasses,
       Iterable<MemberEntity> liveInstanceMembers,
       Iterable<MemberEntity> assignedInstanceMembers,
       Set<TypedefElement> allTypedefs,
       Map<ClassEntity, Set<ClassEntity>> mixinUses,
       Map<ClassEntity, Set<ClassEntity>> typesImplementedBySubclasses,
       Map<ClassEntity, ClassHierarchyNode> classHierarchyNodes,
       Map<ClassEntity, ClassSet> classSets})
       : super(
             elementEnvironment,
             dartTypes,
             commonElements,
             constantSystem,
             nativeData,
             interceptorData,
             backendUsage,
             implementedClasses,
+            liveNativeClasses,
             liveInstanceMembers,
             assignedInstanceMembers,
             allTypedefs,
             mixinUses,
             typesImplementedBySubclasses,
             classHierarchyNodes,
             classSets);
 
   @override
   void registerClosureClass(ClassElement cls) {
@@ skipping 162 matching lines @@
 
   @override
   bool get isFunctionApplyUsed => _backendUsage.isFunctionApplyUsed;
 
   @override
   bool get isMirrorsUsed => _backendUsage.isMirrorsUsed;
 
   @override
   bool get isNoSuchMethodUsed => _backendUsage.isNoSuchMethodUsed;
 }