Handle js interop members in impact computation.

tests/compiler/dart2js/kernel/impact_test.dart

 // Copyright (c) 2016, 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.kernel.impact_test;
 
 import 'package:async_helper/async_helper.dart';
 import 'package:compiler/src/common.dart';
 import 'package:compiler/src/common_elements.dart';
 import 'package:compiler/src/common/names.dart';
@@ skipping 12 matching lines @@
 import 'package:compiler/src/universe/feature.dart';
 import 'package:compiler/src/universe/use.dart';
 import 'package:compiler/src/util/util.dart';
 import '../equivalence/check_helpers.dart';
 import 'compiler_helper.dart';
 import 'test_helpers.dart';
 
 const Map<String, String> SOURCE = const <String, String>{
   // Pretend this is a dart2js_native test to allow use of 'native' keyword.
   'sdk/tests/compiler/dart2js_native/main.dart': r'''
-import 'dart:_foreign_helper';
+@JS()
+library test;
+
+import 'dart:_foreign_helper' as foreign show JS;
+import 'dart:_foreign_helper' hide JS;
 import 'dart:_js_helper';
 import 'dart:_interceptors';
 import 'dart:_native_typed_data';
 import 'dart:indexed_db';
 import 'dart:html';
 import 'dart:html_common';
 import 'dart:math';
 import 'dart:typed_data';
 import 'dart:web_sql';
+import 'package:js/js.dart';
 import 'helper.dart';
 
 main() {
   testEmpty();
   testNull();
   testTrue();
   testFalse();
   testInt();
   testDouble();
   testString();
@@ skipping 142 matching lines @@
   testDynamicPrivateMethodInvoke();
   testJSCall();
   testNativeMethod();
   testNativeMethodCreates();
   testNativeMethodReturns();
   testNativeField(null);
   testMixinInstantiation();
   testNamedMixinInstantiation();
   testGenericMixinInstantiation();
   testGenericNamedMixinInstantiation();
+  testJsInteropMethod();
+  testJsInteropClass();
 }
 
 testEmpty() {}
 testNull() => null;
 testTrue() => true;
 testFalse() => false;
 testInt() => 42;
 testDouble() => 37.5;
 testString() => 'foo';
 testStringInterpolation() => '${0}';
@@ skipping 447 matching lines @@
 List<T> staticGenericMethod<T>(T arg) => [arg];
 testStaticGenericMethod() {
   staticGenericMethod<int>(0);
 }
 
 testInstanceGenericMethod() {
   new GenericClass<int, String>.generative().genericMethod<bool>(false);
 }
 
 testDynamicPrivateMethodInvoke([o]) => o._privateMethod();
-testJSCall() => JS('int|bool|NativeUint8List|Rectangle|IdbFactory|'
+testJSCall() => foreign.JS('int|bool|NativeUint8List|Rectangle|IdbFactory|'
     'SqlDatabase|TypedData|ContextAttributes', '#', null);
 @JSName('foo')
 @SupportedBrowser(SupportedBrowser.CHROME)
 testNativeMethod() native;
 @Creates('int|Null|JSArray')
 testNativeMethodCreates() native;
 @Returns('String|Null|JSArray')
 testNativeMethodReturns() native;
 
 @Native("NativeClass")
 class NativeClass {
   @annotation_Creates_SerializedScriptValue
   final Object field;
 
   factory NativeClass._() { throw new UnsupportedError("Not supported"); }
 }
 testNativeField(NativeClass c) => c.field;
 testMixinInstantiation() => new Sub();
 testNamedMixinInstantiation() => new NamedMixin();
 testGenericMixinInstantiation() => new GenericSub<int, String>();
 testGenericNamedMixinInstantiation() => new GenericNamedMixin<int, String>();
+
+@JS()
+external int testJsInteropMethod();
+
+@JS()
+class JsInteropClass {
+  @JS()
+  external double method();
+}
+
+testJsInteropClass() => new JsInteropClass().method();
 ''',
   'sdk/tests/compiler/dart2js_native/helper.dart': '''
 import 'dart:_js_helper';
 class Class {
   const Class.generative();
   factory Class.fact() => null;
   const factory Class.redirect() = Class.generative;
 }
 class GenericClass<X, Y> {
   const GenericClass.generative();
@@ skipping 182 matching lines @@
         builder.registerFeature(Feature.THROW_EXPRESSION);
         break;
       default:
         builder.registerFeature(feature);
         break;
     }
   }
   impact.nativeData.forEach(builder.registerNativeData);
   return builder;
 }