Pass ClassHierarchy instead of creating it.

pkg/kernel/test/treeshaker_dump.dart

Index: pkg/kernel/test/treeshaker_dump.dart
diff --git a/pkg/kernel/test/treeshaker_dump.dart b/pkg/kernel/test/treeshaker_dump.dart
index 0f8f22b983201901aeb145cfdc66d84355f17df5..16c1c109733496a180abbfdbd16a672a306b728b 100644
--- a/pkg/kernel/test/treeshaker_dump.dart
+++ b/pkg/kernel/test/treeshaker_dump.dart
@@ -4,6 +4,7 @@
 library kernel.treeshaker_dump;
 
 import 'dart:io';
+import 'package:kernel/class_hierarchy.dart';
 import 'package:kernel/core_types.dart';
 import 'package:kernel/kernel.dart';
 import 'package:kernel/transformations/treeshaker.dart';
@@ -66,7 +67,9 @@ main(List<String> args) {
 
   Program program = loadProgramFromBinary(filename);
   CoreTypes coreTypes = new CoreTypes(program);
-  TreeShaker shaker = new TreeShaker(coreTypes, program, strongMode: strong);
+  ClassHierarchy hierarchy = new ClosedWorldClassHierarchy(program);
+  TreeShaker shaker =
+      new TreeShaker(coreTypes, hierarchy, program, strongMode: strong);
   int totalClasses = 0;
   int totalInstantiationCandidates = 0;
   int totalMembers = 0;
@@ -129,7 +132,8 @@ main(List<String> args) {
     StringBuffer before = new StringBuffer();
     new Printer(before, syntheticNames: names).writeProgramFile(program);
     new File(beforeFile).writeAsStringSync('$before');
-    new TreeShaker(coreTypes, program, strongMode: strong).transform(program);
+    new TreeShaker(coreTypes, hierarchy, program, strongMode: strong)
+        .transform(program);
     StringBuffer after = new StringBuffer();
     new Printer(after, syntheticNames: names).writeProgramFile(program);
     new File(afterFile).writeAsStringSync('$after');