Delete dart2js specific private library code

tool/input_sdk/private/annotations.dart

 // Copyright (c) 2013, 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 _js_helper;
 
-/// Tells the optimizing compiler that the annotated method has no
-/// side-effects.
-/// Requires @NoInline() to function correctly.
-class NoSideEffects {
-  const NoSideEffects();
-}
-
 /// Tells the optimizing compiler that the annotated method cannot throw.
 /// Requires @NoInline() to function correctly.
 class NoThrows {
   const NoThrows();
 }
 
 /// Tells the optimizing compiler to not inline the annotated method.
 class NoInline {
   const NoInline();
 }
 
-// Ensures that the annotated method is represented internally using
-// IR nodes ([:value == true:]) or AST nodes ([:value == false:]).
-class IrRepresentation {
-  final bool value;
-  const IrRepresentation(this.value);
-}
-
 /// Marks a class as native and defines its JavaScript name(s).
 class Native {
   final String name;
   const Native(this.name);
 }