Change inference element invariants

pkg/compiler/lib/src/common_elements.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.
 
 // TODO(sigmund): rename and move to common/elements.dart
 library dart2js.type_system;
 
 import 'common/names.dart' show Identifiers, Uris;
 import 'constants/values.dart';
 import 'elements/entities.dart';
@@ skipping 1126 matching lines @@
 
   ClassEntity get expectTrustTypeAnnotationsClass {
     _ensureExpectAnnotations();
     return _expectTrustTypeAnnotationsClass;
   }
 
   ClassEntity get expectAssumeDynamicClass {
     _ensureExpectAnnotations();
     return _expectAssumeDynamicClass;
   }
+
+  bool isForeign(MemberEntity element) => element.library == foreignLibrary;
 }
 
 /// Interface for accessing libraries, classes and members.
 ///
 /// The element environment makes private and injected members directly
 /// available and should therefore not be used to determine scopes.
 ///
 /// The properties exposed are Dart-centric and should therefore, long-term, not
 /// be used during codegen, expect for mirrors.
 // TODO(johnniwinther): Split this into an element environment and a type query
@@ skipping 136 matching lines @@
   // TODO(johnniwinther): Remove this when the resolver is removed.
   DartType getUnaliasedType(DartType type);
 
   /// Returns `true` if [member] a the synthetic getter `loadLibrary` injected
   /// on deferred libraries.
   bool isDeferredLoadLibraryGetter(MemberEntity member);
 
   /// Returns the metadata constants declared on [member].
   Iterable<ConstantValue> getMemberMetadata(MemberEntity member);
 }