Update range errors to agree on the numbers.

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 374 matching lines @@
         super.value(invalidValue, name,
                     (message != null) ? message : "Index out of range");
 
   // Getters inherited from RangeError.
   int get start => 0;
   int get end => length - 1;
 
   String get _errorName => "RangeError";
   String get _errorExplanation {
     assert(_hasValue);
-    String target = Error.safeToString(indexable);
-    var explanation = ": index should be less than $length";
     if (invalidValue < 0) {
-      explanation = ": index must not be negative";
+      return ": index must not be negative";
     }
-    return explanation;
+    if (length == 0) {
+      return ": no indices are valid";
+    }
+    return ": index should be less than $length";
   }
 }
 
 
 /**
  * Error thrown when control reaches the end of a switch case.
  *
  * The Dart specification requires this error to be thrown when
  * control reaches the end of a switch case (except the last case
  * of a switch) without meeting a break or similar end of the control
@@ skipping 151 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";
 }