Flatten inferrer implementation

pkg/compiler/lib/src/inferrer/closure_tracer.dart

Index: pkg/compiler/lib/src/inferrer/closure_tracer.dart
diff --git a/pkg/compiler/lib/src/inferrer/closure_tracer.dart b/pkg/compiler/lib/src/inferrer/closure_tracer.dart
index a757a7b89f4e98ac28e9cfb7ce47b027b895e6a5..0dacfde3c1bcabf2639b8dc8f293d9a4131536ff 100644
--- a/pkg/compiler/lib/src/inferrer/closure_tracer.dart
+++ b/pkg/compiler/lib/src/inferrer/closure_tracer.dart
@@ -10,17 +10,21 @@ import '../js_backend/backend_helpers.dart';
 import '../types/types.dart' show TypeMask;
 import '../universe/selector.dart' show Selector;
 import 'debug.dart' as debug;
+import 'inferrer_engine.dart';
 import 'node_tracer.dart';
 import 'type_graph_nodes.dart';
 
-class ClosureTracerVisitor extends TracerVisitor<ApplyableTypeInformation> {
+class ClosureTracerVisitor extends TracerVisitor {
   final Iterable<FunctionElement> tracedElements;
   final List<CallSiteTypeInformation> _callsToAnalyze =
       new List<CallSiteTypeInformation>();
 
-  ClosureTracerVisitor(this.tracedElements, tracedType, inferrer)
+  ClosureTracerVisitor(this.tracedElements, ApplyableTypeInformation tracedType,
+      InferrerEngine inferrer)
       : super(tracedType, inferrer);
 
+  ApplyableTypeInformation get tracedType => super.tracedType;
+
   void run() {
     analyze();
     if (!continueAnalyzing) return;