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

pkg/compiler/lib/src/diagnostic_listener.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 DiagnosticListener {
-  // TODO(karlklose): rename log to something like reportInfo.
-  void log(message);
-
-  void internalError(Spannable spannable, message);
-
-  SourceSpan spanFromSpannable(Spannable node);
-
-  /// Reports an error and terminates computation immediately.
-  void reportFatalError(Spannable node, MessageKind errorCode,
-                        [Map arguments = const {}]);
-
-  void reportError(Spannable node, MessageKind errorCode,
-                   [Map arguments = const {}]);
-
-  void reportWarning(Spannable node, MessageKind errorCode,
-                     [Map arguments = const {}]);
-
-  void reportHint(Spannable node, MessageKind errorCode,
-                  [Map arguments = const {}]);
-
-  void reportInfo(Spannable node, MessageKind errorCode,
-                  [Map arguments = const {}]);
-
-  // TODO(ahe): We should not expose this here.  Perhaps a
-  // [SourceSpan] should implement [Spannable], and we should have a
-  // way to construct a [SourceSpan] from a [Spannable] and an
-  // [Element].
-  withCurrentElement(Element element, f());
-}