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

pkg/compiler/lib/src/resolution/label_scope.dart

 // Copyright (c) 2015, 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.resolution.label_scope;
 
-import '../elements/elements.dart' show JumpTarget, LabelDefinition;
+import '../elements/jumps.dart';
 import '../util/util.dart' show Link;
 
 abstract class LabelScope {
   LabelScope get outer;
   LabelDefinition lookup(String label);
 }
 
 class LabeledStatementLabelScope implements LabelScope {
   final LabelScope outer;
   final Map<String, LabelDefinition> labels;
@@ skipping 77 matching lines @@
     labels = new SwitchLabelScope(labels, continueElements);
     nestingLevel++;
   }
 
   void exitSwitch() {
     nestingLevel--;
     breakTargetStack = breakTargetStack.tail;
     labels = labels.outer;
   }
 }