Fix hints reported by analyzer.

pkg/compiler/lib/src/ssa/jump_handler.dart

 // Copyright (c) 2016, 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 '../common.dart';
 import '../elements/elements.dart';
 import '../tree/tree.dart' as ast;
 
-import 'builder.dart';
 import 'graph_builder.dart';
 import 'locals_handler.dart';
 import 'nodes.dart';
 
 /// A single break/continue instruction.
 class _JumpHandlerEntry {
   final HJump jumpInstruction;
   final LocalsHandler locals;
   bool isBreak() => jumpInstruction is HBreak;
   bool isContinue() => jumpInstruction is HContinue;
@@ skipping 205 matching lines @@
   }
 
   void close() {
     // The mapping from TargetElement to JumpHandler is no longer needed.
     for (JumpTarget target in targetIndexMap.keys) {
       builder.jumpTargets.remove(target);
     }
     super.close();
   }
 }