corelib: Do not print value in ArgumentError.notNull

sdk/lib/core/errors.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 dart.core;
 
 /**
  * Error objects thrown in the case of a program failure.
  *
  * An `Error` object represents a program failure that the programmer
@@ skipping 147 matching lines @@
    * interface method's argument name (or just rename arguments to match).
    */
   ArgumentError.value(value,
                       [String this.name,
                        String this.message])
       : invalidValue = value,
         _hasValue = true;
 
   /**
    * Create an argument error for a `null` argument that must not be `null`.
-   *
-   * Shorthand for calling [ArgumentError.value] with a `null` value and a
-   * message of `"Must not be null"`.
    */
-  ArgumentError.notNull([String name])
-      : this.value(null, name, "Must not be null");
+  ArgumentError.notNull([this.name])
+      : _hasValue = false,
+        message = "Must not be null",
+        invalidValue = null;
 
   // Helper functions for toString overridden in subclasses.
   String get _errorName => "Invalid argument${!_hasValue ? "(s)" : ""}";
   String get _errorExplanation => "";
 
   String toString() {
     String nameString = "";
     if (name != null) {
       nameString = " ($name)";
     }
@@ skipping 381 matching lines @@
  * the first time it is read. If evaluating the initializer expression causes
  * another read of the variable, this error is thrown.
  */
 class CyclicInitializationError extends Error {
   final String variableName;
   CyclicInitializationError([this.variableName]);
   String toString() => variableName == null
       ? "Reading static variable during its initialization"
       : "Reading static variable '$variableName' during its initialization";
 }