Assert that we don't mix K and J elements

pkg/compiler/lib/src/native/behavior.dart

 // Copyright (c) 2014, 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.
 
 import '../common.dart';
 import '../common/backend_api.dart' show ForeignResolver;
 import '../common/resolution.dart' show ParsingContext, Resolution;
 import '../compiler.dart' show Compiler;
 import '../constants/values.dart';
 import '../common_elements.dart' show CommonElements;
@@ skipping 756 matching lines @@
   static NativeBehavior ofMethodElement(
       MethodElement element, Compiler compiler,
       {bool isJsInterop}) {
     ResolutionFunctionType type = element.computeType(compiler.resolution);
     List<ConstantValue> metadata = <ConstantValue>[];
     for (MetadataAnnotation annotation in element.implementation.metadata) {
       annotation.ensureResolved(compiler.resolution);
       metadata.add(compiler.constants.getConstantValue(annotation.constant));
     }
 
-    BehaviorBuilder builder =
-        new ResolverBehaviorBuilder(compiler, compiler.backend.nativeBasicData);
+    BehaviorBuilder builder = new ResolverBehaviorBuilder(
+        compiler, compiler.frontendStrategy.nativeBasicData);
     return builder.buildMethodBehavior(
         type, metadata, lookupFromElement(compiler.resolution, element),
         isJsInterop: isJsInterop);
   }
 
   static NativeBehavior ofFieldElementLoad(
       MemberElement element, Compiler compiler,
       {bool isJsInterop}) {
     Resolution resolution = compiler.resolution;
     ResolutionDartType type = element.computeType(resolution);
     List<ConstantValue> metadata = <ConstantValue>[];
     for (MetadataAnnotation annotation in element.implementation.metadata) {
       annotation.ensureResolved(compiler.resolution);
       metadata.add(compiler.constants.getConstantValue(annotation.constant));
     }
 
-    BehaviorBuilder builder =
-        new ResolverBehaviorBuilder(compiler, compiler.backend.nativeBasicData);
+    BehaviorBuilder builder = new ResolverBehaviorBuilder(
+        compiler, compiler.frontendStrategy.nativeBasicData);
     return builder.buildFieldLoadBehavior(
         type, metadata, lookupFromElement(resolution, element),
         isJsInterop: isJsInterop);
   }
 
   static NativeBehavior ofFieldElementStore(
       MemberElement field, Compiler compiler) {
-    BehaviorBuilder builder =
-        new ResolverBehaviorBuilder(compiler, compiler.backend.nativeBasicData);
+    BehaviorBuilder builder = new ResolverBehaviorBuilder(
+        compiler, compiler.frontendStrategy.nativeBasicData);
     ResolutionDartType type = field.computeType(compiler.resolution);
     return builder.buildFieldStoreBehavior(type);
   }
 
   static TypeLookup lookupFromElement(Resolution resolution, Element element) {
     ResolutionDartType lookup(String name, {bool required}) {
       Element e = element.buildScope().lookup(name);
       if (e == null || e is! ClassElement) {
         if (required) {
           resolution.reporter.reportErrorMessage(element, MessageKind.GENERIC,
@@ skipping 229 matching lines @@
   @override
   bool get trustJSInteropTypeAnnotations =>
       compiler.options.trustJSInteropTypeAnnotations;
 
   @override
   DiagnosticReporter get reporter => compiler.reporter;
 
   @override
   Resolution get resolution => compiler.resolution;
 }