Remove unused API.

dart/sdk/lib/_internal/compiler/implementation/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.
 
 part of dart2js;
 
 abstract class Operation {
   String get name;
-  bool isUserDefinable();
 }
 
 abstract class UnaryOperation extends Operation {
   /** Returns [:null:] if it was unable to fold the operation. */
   Constant fold(Constant constant);
-  apply(value);
 }
 
 abstract class BinaryOperation extends Operation {
   /** Returns [:null:] if it was unable to fold the operation. */
   Constant fold(Constant left, Constant right);
   apply(left, right);
 }
 
 /**
  * A [ConstantSystem] is responsible for creating constants and folding them.
@@ skipping 44 matching lines @@
   bool isBool(Constant constant);
   /** Returns true if the [constant] is null at runtime. */
   bool isNull(Constant constant);
 
   Operation lookupUnary(String operator) {
     if (operator == '-') return negate;
     if (operator == '~') return bitNot;
     return null;
   }
 }