Reapply "Use backend targets to run Kernel transformations in Fasta"

pkg/front_end/lib/src/fasta/dill/dill_target.dart

Index: pkg/front_end/lib/src/fasta/dill/dill_target.dart
diff --git a/pkg/front_end/lib/src/fasta/dill/dill_target.dart b/pkg/front_end/lib/src/fasta/dill/dill_target.dart
index c628e52b2f264bc12876a15fa5b77cfa5bb2fb71..8906c3c981ec6cd95a4ced2ad089b50a812557c6 100644
--- a/pkg/front_end/lib/src/fasta/dill/dill_target.dart
+++ b/pkg/front_end/lib/src/fasta/dill/dill_target.dart
@@ -8,7 +8,7 @@ import 'dart:async' show Future;
 
 import 'package:kernel/ast.dart' show Class;
 
-import 'package:kernel/target/targets.dart' show getTarget;
+import 'package:kernel/target/targets.dart' show getTarget, TargetFlags;
 
 import '../errors.dart' show internalError;
 import '../kernel/kernel_builder.dart' show ClassBuilder;
@@ -23,8 +23,10 @@ class DillTarget extends TargetImplementation {
   DillLoader loader;
 
   DillTarget(
-      Ticker ticker, TranslateUri uriTranslator, String backendTargetName)
-      : super(ticker, uriTranslator, getTarget(backendTargetName, null)) {
+      Ticker ticker, TranslateUri uriTranslator, String backendTargetName,
+      {TargetFlags flags})
+      : super(ticker, uriTranslator,
+            getTarget(backendTargetName, flags ?? new TargetFlags())) {

[ahe, 2017/06/02 14:07:46]

Since we need to pass in TargetFlags now, perhaps it would be a good time to
switch from

String backendTargetName

to

Target backendTarget

[Dmitry Stefantsov, 2017/06/02 14:28:53]

Sorry for missing this comment before landing. I agree. I'll create a new CL
with this change.

[ahe, 2017/06/02 14:30:19]

Great!

     loader = new DillLoader(this);
   }