Parameterize and move JumpTarget/LabelDefition to elements/jumps.dart

pkg/compiler/lib/src/ssa/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.
 
 import 'dart:math' as math;
 import 'dart:collection' show Queue;
 import '../common.dart';
 import '../common/codegen.dart' show CodegenRegistry, CodegenWorkItem;
 import '../common/tasks.dart' show CompilerTask;
 import '../constants/constant_system.dart';
 import '../constants/values.dart';
 import '../common_elements.dart' show CommonElements;
-import '../elements/elements.dart'
-    show JumpTarget, LabelDefinition, MethodElement;
+import '../elements/elements.dart' show MethodElement;
 import '../elements/entities.dart';
+import '../elements/jumps.dart';
 import '../elements/types.dart';
 import '../io/source_information.dart';
 import '../js/js.dart' as js;
 import '../js_backend/interceptor_data.dart';
 import '../js_backend/backend.dart';
 import '../js_backend/checked_mode_helpers.dart';
 import '../js_backend/native_data.dart';
 import '../js_backend/namer.dart';
 import '../js_backend/runtime_types.dart';
 import '../js_emitter/code_emitter_task.dart';
@@ skipping 3015 matching lines @@
     return _closedWorld.anyStrictSubclassOf(cls, (ClassEntity subclass) {
       return !_rtiSubstitutions.isTrivialSubstitution(subclass, cls);
     });
   }
 
   @override
   void visitRef(HRef node) {
     visit(node.value);
   }
 }