Move enableNative to target, turn it on by default

pkg/front_end/lib/src/fasta/source/outline_builder.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 fasta.outline_builder;
 
 import 'package:kernel/ast.dart' show ProcedureKind;
 
 import '../fasta_codes.dart' show FastaMessage, codeExpectedBlockToSkip;
 
@@ skipping 36 matching lines @@
 
 class OutlineBuilder extends UnhandledListener {
   final SourceLibraryBuilder library;
 
   final bool enableNative;
 
   String nativeMethodName;
 
   OutlineBuilder(SourceLibraryBuilder library)
       : library = library,
-        enableNative = (library.uri.scheme == "dart" || library.isPatch);
+        enableNative = library.loader.target.enableNative(library);
 
   @override
   Uri get uri => library.fileUri;
 
   @override
   int popCharOffset() => pop();
 
   List<String> popIdentifierList(int count) {
     if (count == 0) return null;
     List<String> list = new List<String>.filled(count, null, growable: true);
@@ skipping 729 matching lines @@
   Link<Token> handleMemberName(Link<Token> identifiers) {
     if (!enableNative || identifiers.isEmpty) return identifiers;
     return removeNativeClause(identifiers);
   }
 
   @override
   void debugEvent(String name) {
     // printEvent(name);
   }
 }