dart2js: Constant fold num.round()

pkg/compiler/lib/src/constants/constant_system.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.
 
 library dart2js.constant_system;
 
 import '../compiler.dart' show Compiler;
 import '../dart_types.dart';
 import '../resolution/operators.dart';
 import '../tree/dartstring.dart' show DartString;
@@ skipping 36 matching lines @@
   BinaryOperation get modulo;
   BinaryOperation get multiply;
   UnaryOperation get negate;
   UnaryOperation get not;
   BinaryOperation get shiftLeft;
   BinaryOperation get shiftRight;
   BinaryOperation get subtract;
   BinaryOperation get truncatingDivide;
 
   BinaryOperation get codeUnitAt;
+  UnaryOperation get round;
 
   const ConstantSystem();
 
   ConstantValue createInt(int i);
   ConstantValue createDouble(double d);
   ConstantValue createString(DartString string);
   ConstantValue createBool(bool value);
   ConstantValue createNull();
   ConstantValue createList(InterfaceType type, List<ConstantValue> values);
   // TODO(johnniwinther): Remove the need for [compiler].
@@ skipping 70 matching lines @@
         return greaterEqual;
       case BinaryOperatorKind.EQ:
         return equal;
       case BinaryOperatorKind.IF_NULL:
         return ifNull;
       default:
         return null;
     }
   }
 }