Fix incremental kernel generator.

pkg/front_end/lib/src/incremental_kernel_generator_impl.dart

Index: pkg/front_end/lib/src/incremental_kernel_generator_impl.dart
diff --git a/pkg/front_end/lib/src/incremental_kernel_generator_impl.dart b/pkg/front_end/lib/src/incremental_kernel_generator_impl.dart
index b761d73188bf97429f77d1ed86326157d2577d67..7761f31bb554c87ac46a83e389ee2928acd535e8 100644
--- a/pkg/front_end/lib/src/incremental_kernel_generator_impl.dart
+++ b/pkg/front_end/lib/src/incremental_kernel_generator_impl.dart
@@ -101,7 +101,7 @@ class IncrementalKernelGeneratorImpl implements IncrementalKernelGenerator {
 
       CanonicalName nameRoot = new CanonicalName.root();
       DillTarget dillTarget =
-          new DillTarget(new Ticker(isVerbose: false), _uriTranslator);
+          new DillTarget(new Ticker(isVerbose: false), _uriTranslator, "vm");

[scheglov, 2017/05/22 16:05:06]

Why not use new VmTarget() directly?
Why should we go through additional map lookup and use magic names anyway?

[ahe, 2017/05/22 16:09:56]

Because I'm assuming that this is an option that should be specified on the
command line.

 
       List<_LibraryCycleResult> results = [];
       await _logger.runAsync('Compute results for cycles', () async {