Pass a Target instance to DillTarget instead of its name

pkg/front_end/lib/kernel_generator.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.
 
 /// Defines the front-end API for converting source code to Dart Kernel objects.
 library front_end.kernel_generator;
 
 import 'compiler_options.dart';
 import 'dart:async' show Future;
 import 'dart:async';
 import 'package:front_end/src/base/processed_options.dart';
 import 'src/fasta/dill/dill_target.dart' show DillTarget;
 import 'src/fasta/errors.dart' show InputError;
 import 'src/fasta/kernel/kernel_target.dart' show KernelTarget;
 import 'package:kernel/kernel.dart' show Program;
 import 'package:kernel/target/targets.dart' show TargetFlags;
+import 'package:kernel/target/vm_fasta.dart' show VmFastaTarget;
 import 'src/fasta/ticker.dart' show Ticker;
 import 'src/fasta/translate_uri.dart' show TranslateUri;
 import 'src/simple_error.dart';
 
 /// Generates a kernel representation of the program whose main library is in
 /// the given [source].
 ///
 /// Intended for whole program (non-modular) compilation.
 ///
 /// Given the Uri of a file containing a program's `main` method, this function
@@ skipping 19 matching lines @@
     return report("Entry-point file not found: $source");
   }
 
   var pOptions = new ProcessedOptions(options);
 
   if (!await pOptions.validateOptions()) return null;
 
   try {
     TranslateUri uriTranslator = await pOptions.getUriTranslator();
 
-    var dillTarget = new DillTarget(
-        new Ticker(isVerbose: false), uriTranslator, "vm_fasta",
-        flags: new TargetFlags(strongMode: options.strongMode));
+    var dillTarget = new DillTarget(new Ticker(isVerbose: false), uriTranslator,
+        new VmFastaTarget(new TargetFlags(strongMode: options.strongMode)));
     var summary = await pOptions.sdkSummaryProgram;
     if (summary != null) {
       dillTarget.loader.appendLibraries(summary);
     }
 
     var kernelTarget =
         new KernelTarget(options.fileSystem, dillTarget, uriTranslator);
     kernelTarget.read(source);
 
     await dillTarget.buildOutlines();
@@ skipping 74 matching lines @@
     }
   }
 
   var pOptions = new ProcessedOptions(options);
 
   if (!await pOptions.validateOptions()) return null;
 
   try {
     TranslateUri uriTranslator = await pOptions.getUriTranslator();
 
-    var dillTarget = new DillTarget(
-        new Ticker(isVerbose: false), uriTranslator, "vm_fasta",
-        flags: new TargetFlags(strongMode: options.strongMode));
+    var dillTarget = new DillTarget(new Ticker(isVerbose: false), uriTranslator,
+        new VmFastaTarget(new TargetFlags(strongMode: options.strongMode)));
     var summary = await pOptions.sdkSummaryProgram;
     if (summary != null) {
       dillTarget.loader.appendLibraries(summary);
     }
 
     // TODO(sigmund): this is likely not going to work if done naively: if
     // summaries contain external references we need to ensure they are loaded
     // in a specific order.
     for (var inputSummary in await pOptions.inputSummariesPrograms) {
       dillTarget.loader.appendLibraries(inputSummary);
@@ skipping 12 matching lines @@
       kernelTarget.errors.forEach(report);
       return null;
     }
 
     return program;
   } on InputError catch (e) {
     options.onError(new SimpleError(e.format()));
     return null;
   }
 }