Move dart2js from sdk/lib/_internal/compiler to pkg/compiler

pkg/compiler/lib/src/resolved_visitor.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.
 
 part of dart2js;
 
 abstract class ResolvedVisitor<R> extends Visitor<R> {
   TreeElements elements;
 
   ResolvedVisitor(this.elements);
@@ skipping 59 matching lines @@
 
   R visitAssert(Send node);
 
   void internalError(String reason, {Node node});
 
   R visitNode(Node node) {
     internalError("Unhandled node", node: node);
     return null;
   }
 }