Move code for instantiating Invocation to Target.

pkg/front_end/lib/src/fasta/target_implementation.dart

Index: pkg/front_end/lib/src/fasta/target_implementation.dart
diff --git a/pkg/front_end/lib/src/fasta/target_implementation.dart b/pkg/front_end/lib/src/fasta/target_implementation.dart
index 6c284568658a624a3b0bbefeccc63c031d72cd7f..fc39fce98b74b7ca271e39e9e62a1f15c7b89376 100644
--- a/pkg/front_end/lib/src/fasta/target_implementation.dart
+++ b/pkg/front_end/lib/src/fasta/target_implementation.dart
@@ -4,7 +4,7 @@
 
 library fasta.target_implementation;
 
-import 'package:kernel/target/vm.dart' show VmTarget;
+import 'package:kernel/target/targets.dart' as backend show Target;
 
 import 'builder/builder.dart' show Builder, ClassBuilder, LibraryBuilder;
 
@@ -25,11 +25,15 @@ import 'translate_uri.dart' show TranslateUri;
 /// Provides the implementation details used by a loader for a target.
 abstract class TargetImplementation extends Target {
   final TranslateUri uriTranslator;
+
+  final backend.Target backendTarget;
+
   Builder cachedCompileTimeError;
   Builder cachedAbstractClassInstantiationError;
   Builder cachedNativeAnnotation;
 
-  TargetImplementation(Ticker ticker, this.uriTranslator) : super(ticker);
+  TargetImplementation(Ticker ticker, this.uriTranslator, this.backendTarget)
+      : super(ticker);
 
   /// Creates a [LibraryBuilder] corresponding to [uri], if one doesn't exist
   /// already.
@@ -79,7 +83,7 @@ abstract class TargetImplementation extends Target {
   }
 
   void loadExtraRequiredLibraries(Loader loader) {
-    for (String uri in new VmTarget(null).extraRequiredLibraries) {
+    for (String uri in backendTarget.extraRequiredLibraries) {
       loader.read(Uri.parse(uri));
     }
   }