Move WorldImpact to universe/world_impact.dart

pkg/compiler/lib/src/common/codegen.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library dart2js.common.codegen;
 
 import '../common.dart';
 import '../compiler.dart' show
     Compiler;
 import '../constants/values.dart' show
     ConstantValue;
 import '../dart_types.dart' show
     DartType,
     InterfaceType;
 import '../elements/elements.dart' show
     AstElement,
     ClassElement,
     Element,
     FunctionElement,
     LocalFunctionElement;
 import '../enqueue.dart' show
-    CodegenEnqueuer,
-    WorldImpact;
+    CodegenEnqueuer;
 import '../js_backend/js_backend.dart' show
     JavaScriptBackend;
 import '../resolution/tree_elements.dart' show
     TreeElements;
 import '../universe/selector.dart' show
     Selector;
 import '../universe/universe.dart' show
     UniverseSelector;
+import '../universe/world_impact.dart' show
+    WorldImpact;
 import '../util/util.dart' show
     Setlet;
 import 'registry.dart' show
     Registry;
 import 'work.dart' show
     ItemCompilationContext,
     WorkItem;
 
 // TODO(johnniwinther): Split this class into interface and implementation.
 // TODO(johnniwinther): Move this implementation to the JS backend.
@@ skipping 154 matching lines @@
 
   TreeElements get resolutionTree => element.resolvedAst.elements;
 
   WorldImpact run(Compiler compiler, CodegenEnqueuer world) {
     if (world.isProcessed(element)) return const WorldImpact();
 
     registry = new CodegenRegistry(compiler, resolutionTree);
     return compiler.codegen(this, world);
   }
 }