pkg/compiler: fix imports

pkg/compiler/lib/src/tree_ir/optimization/pull_into_initializers.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 tree_ir.optimization.pull_into_initializers;
 
+import '../tree_ir_nodes.dart';
 import 'optimization.dart' show Pass;
-import '../tree_ir_nodes.dart';
 
 /// Where a variable has been assigned.
 enum AssignArea {
   /// The variable is only assigned in the initializer block.
   Initializer,
 
   // The variable has at least one assignment outside the initializer block.
   Anywhere,
 }
 
@@ skipping 350 matching lines @@
 
   @override
   Expression visitForeignExpression(ForeignExpression node) {
     rewriteList(node.arguments);
     if (node.nativeBehavior.sideEffects.hasSideEffects()) {
       ++impureCounter;
     }
     return node;
   }
 }