Remove unused imports to make analyzer happy

pkg/kernel/lib/transformations/closure/info.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.
 
 library kernel.transformations.closure.info;
 
 import '../../ast.dart'
     show
         Class,
         Constructor,
         Field,
-        FieldInitializer,
         FunctionDeclaration,
         FunctionNode,
-        LocalInitializer,
         Member,
         Name,
         Procedure,
         ProcedureKind,
         PropertyGet,
-        RedirectingInitializer,
-        SuperInitializer,
         ThisExpression,
         TypeParameter,
         TypeParameterType,
         VariableDeclaration,
         VariableGet,
         VariableSet;
 
 import '../../visitor.dart' show RecursiveVisitor;
 
 class ClosureInfo extends RecursiveVisitor {
@@ skipping 207 matching lines @@
 
   saveCurrentFunction(void f()) {
     var saved = currentFunction;
     try {
       f();
     } finally {
       currentFunction = saved;
     }
   }
 }