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

pkg/docgen/lib/src/models/annotation.dart

 // Copyright (c) 2014, 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 docgen.models.annotation;
 
 import '../exports/source_mirrors.dart';
 
 import '../exports/dart2js_mirrors.dart' show ResolvedNode;
 
 import '../library_helpers.dart';
 
 import 'library.dart';
 import 'mirror_based.dart';
 
 import 'dart:mirrors';
-import 'package:compiler/src/tree/tree.dart';
+import 'package:compiler/implementation/tree/tree.dart';
 
 /// Holds the name of the annotation, and its parameters.
 class Annotation extends MirrorBased<ClassMirror> {
   /// The class of this annotation.
   DeclarationMirror mirror;
   Send node;
   final Library owningLibrary;
   List<String> parameters;
 
   Annotation(ResolvedNode resolvedNode, this.owningLibrary) {
@@ skipping 77 matching lines @@
     addToken(node.beginToken);
     if (recursionLevel == 1) sb.clear();
     if (node.nodes != null) {
       recursionLevel++;
       unparseNodeListFrom(node, node.nodes);
       recursionLevel--;
     }
     if (node.endToken != null) write(node.endToken.value);
   }
 }