Move enableNative to target, turn it on by default

pkg/compiler/lib/src/kernel/fasta_support.dart

Index: pkg/compiler/lib/src/kernel/fasta_support.dart
diff --git a/pkg/compiler/lib/src/kernel/fasta_support.dart b/pkg/compiler/lib/src/kernel/fasta_support.dart
index 16fc8da72ee23c46d95721e794a00c90eb48beaf..9d6a90fa50609303fdb762373115a3beadd8e083 100644
--- a/pkg/compiler/lib/src/kernel/fasta_support.dart
+++ b/pkg/compiler/lib/src/kernel/fasta_support.dart
@@ -22,6 +22,8 @@ import 'package:front_end/physical_file_system.dart';
 import 'package:front_end/src/fasta/kernel/utils.dart';
 import 'package:kernel/ast.dart' show Source;
 
+import 'package:front_end/src/fasta/builder/library_builder.dart'
+    show LibraryBuilder;
 import 'package:front_end/src/fasta/compiler_context.dart' show CompilerContext;
 import 'package:front_end/src/fasta/dill/dill_target.dart' show DillTarget;
 import 'package:front_end/src/fasta/fasta.dart' show CompileTask;
@@ -33,6 +35,8 @@ import 'package:front_end/src/scanner/token.dart' show Token;
 import 'package:front_end/src/fasta/ticker.dart' show Ticker;
 import 'package:front_end/src/fasta/translate_uri.dart' show TranslateUri;
 
+import 'package:compiler/src/native/native.dart' show maybeEnableNative;
+
 /// Generates a platform.dill file containing the compiled Kernel IR of the
 /// dart2js SDK.
 Future compilePlatform(Uri patchedSdk, Uri fullOutput,
@@ -86,6 +90,9 @@ class KernelTargetForDart2js extends KernelTarget {
       : super(PhysicalFileSystem.instance, target, uriTranslator, strongMode,
             uriToSource);
 
+  @override
+  bool enableNative(LibraryBuilder library) => maybeEnableNative(library.uri);
+
   @override
   Token skipNativeClause(Token token) => _skipNative(token);