Add some ArgumentError and RangeError constructors that capture more information.

sdk/lib/convert/ascii.dart

 // Copyright (c) 2013, 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.convert;
 
 /**
  * An instance of the default implementation of the [AsciiCodec].
  *
  * This instance provides a convenient access to the most common ASCII
@@ skipping 274 matching lines @@
       if ((source[i] & ~_ASCII_MASK) != 0) {
         throw new FormatException("Source contains non-ASCII bytes.");
       }
     }
     _sink.add(new String.fromCharCodes(source));
   }
 
   void addSlice(List<int> source, int start, int end, bool isLast) {
     final int length = source.length;
     if (start < 0 || start > length) {
-      throw new RangeError.range(start, 0, length - 1);
+      throw new RangeError.range(start, 0, length);
     }
     if (end < start || end > length) {
-      throw new RangeError.range(end, start, length - 1);
+      throw new RangeError.range(end, start, length);
     }
     if (start < end) {
       if (start != 0 || end != length) {
         source = source.sublist(start, end);
       }
       add(source);
     }
     if (isLast) close();
   }
 }