IllegalArgumentException expects a string.

compiler/lib/implementation/array.dart

 // Copyright (c) 2011, 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.
 
 class ArrayFactory {
   factory Array<E>.from(Iterable<E> other) {
     Array<E> array = new Array<E>();
     for (final e in other) {
       array.add(e);
     }
@@ skipping 11 matching lines @@
     }
     return array;
   }
 
   factory Array<E>([int length = null]) {
     bool isFixed = true;
     if (length === null) {
       length = 0;
       isFixed = false;
     } else if (length < 0) {
-      throw new IllegalArgumentException(length);
+      throw new IllegalArgumentException("negative length $length");
     }
     // TODO(floitsch): make array creation more efficient. Currently we allocate
     // a new TypeToken at every allocation. Either we can optimize them away,
     // or we need to find other ways to pass type-information from Dart to JS.
     ObjectArray array = _new(new TypeToken<E>(), length);
     array._isFixed = isFixed;
     return array;
   }
 
   static ObjectArray _new(TypeToken typeToken, int length) native;
@@ skipping 21 matching lines @@
     }
     return list;
   }
 
   factory List<E>([int length = null]) {
     bool isFixed = true;
     if (length === null) {
       length = 0;
       isFixed = false;
     } else if (length < 0) {
-      throw new IllegalArgumentException(length);
+      throw new IllegalArgumentException("negative length $length");
     }
     // TODO(floitsch): make array creation more efficient. Currently we allocate
     // a new TypeToken at every allocation. Either we can optimize them away,
     // or we need to find other ways to pass type-information from Dart to JS.
     ObjectArray list = _new(new TypeToken<E>(), length);
     list._isFixed = isFixed;
     return list;
   }
 
   static ObjectArray _new(TypeToken typeToken, int length) native;
@@ skipping 67 matching lines @@
 
   void setRange(int start, int length, List<T> from, [int startFrom = 0]) {
     if (_isFixed) {
       throw const UnsupportedOperationException(
           "Cannot remove range of a non-extendable array");
     }
     if (length == 0) {
       return;
     }
     if (length < 0) {
-      throw const IllegalArgumentException();
+      throw new IllegalArgumentException("negative length $length");
     }
     Arrays.copy(from, startFrom, this, start, length);
   }
 
   void removeRange(int start, int length) {
     if (_isFixed) {
       throw const UnsupportedOperationException(
           "Cannot remove range of a non-extendable array");
     }
     if (length == 0) {
       return;
     }
     if (length < 0) {
-      throw const IllegalArgumentException();
+      throw new IllegalArgumentException("negative length $length");
     }
     if (start < 0 || start >= this.length) {
       throw new IndexOutOfRangeException(start);
     }
     if (start + length > this.length) {
       throw new IndexOutOfRangeException(start + length);
     }
     _splice(start, length);
   }
 
@@ skipping 116 matching lines @@
   }
 
   static Array _newArray(int len) native {
     return new Array(len);
   }
 
   static void _throwIndexOutOfRangeException(int index) native {
     throw new IndexOutOfRangeException(index);
   }
 }