More features handled in kernel impact.

pkg/compiler/lib/src/js_backend/backend_impact.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 dart2js.js_helpers.impact;
 
 import '../compiler.dart' show Compiler;
 import '../core_types.dart' show CommonElements;
 import '../dart_types.dart' show InterfaceType;
 import '../elements/elements.dart' show ClassElement, Element;
@@ skipping 288 matching lines @@
 
   BackendImpact get constSymbol {
     if (_constSymbol == null) {
       _constSymbol = new BackendImpact(
           instantiatedClasses: [commonElements.symbolClass],
           staticUses: [commonElements.symbolConstructor.declaration]);
     }
     return _constSymbol;
   }
 
-  BackendImpact _incDecOperation;
-
-  BackendImpact get incDecOperation {
-    if (_incDecOperation == null) {
-      _incDecOperation =
-          _needsInt('Needed for the `+ 1` or `- 1` operation of ++/--.');
-    }
-    return _incDecOperation;
-  }
-
   /// Helper for registering that `int` is needed.
   BackendImpact _needsInt(String reason) {
     // TODO(johnniwinther): Register [reason] for use in dump-info.
     return intValues;
   }
 
   /// Helper for registering that `List` is needed.
   BackendImpact _needsList(String reason) {
     // TODO(johnniwinther): Register [reason] for use in dump-info.
     return listValues;
@@ skipping 268 matching lines @@
   BackendImpact _closure;
 
   BackendImpact get closure {
     if (_closure == null) {
       _closure = new BackendImpact(
           instantiatedClasses: [commonElements.functionClass]);
     }
     return _closure;
   }
 }