Improve the error messages for IndexOutOfRangeException.

corelib/src/exceptions.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.
 
 // Exceptions are thrown either by the VM or from Dart code.
 
 /**
  * Interface implemented by all core library exceptions.
  */
 interface Exception default ExceptionImplementation {
   const Exception([var msg]);
 }
 
 
 /**
  * Exception thrown because of an index outside of the valid range.
  */
 class IndexOutOfRangeException implements Exception {
-  const IndexOutOfRangeException(int this._index);
-  String toString() => "IndexOutOfRangeException: $_index";
-  final int _index;
+  const IndexOutOfRangeException(this._value);
+
+  String toString() => "IndexOutOfRangeException: $_value";
+
+  final _value;
 }
 
 
 /**
  * Exception thrown because of attempt to modify an immutable object.
  */
 class IllegalAccessException implements Exception {
   const IllegalAccessException();
   String toString() => "Attempt to modify an immutable object";
 }
@@ skipping 141 matching lines @@
   String toString() => "IllegalJSRegExpException: '$_pattern' '$_errmsg'";
   final String _pattern;
   final String _errmsg;
 }
 
 
 class IntegerDivisionByZeroException implements Exception {
   const IntegerDivisionByZeroException();
   String toString() => "IntegerDivisionByZeroException";
 }