Added nextIntRange to dartvm and dart2js.

runtime/lib/math_patch.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.
 
 // A VM patch of the dart:math library.
 patch num pow(num x, num exponent) => MathNatives.pow(x, exponent);
 patch double atan2(num a, num b) => MathNatives.atan2(a, b);
 patch double sin(num x) => MathNatives.sin(x);
 patch double cos(num x) => MathNatives.cos(x);
 patch double tan(num x) => MathNatives.tan(x);
@@ skipping 50 matching lines @@
 
     var rnd32;
     var result;
     do {
       rnd32 = _nextInt32();
       result = rnd32 % max;
     } while ((rnd32 - result + max) >= _POW2_32);
     return result;
   }
 
+int nextIntRange(int min, int max) {
+    int range = max - min;
+    if (range <= 0) {

[floitsch, 2013/11/18 13:36:03]

Doesn't test if max or min is negative.

+      throw new ArgumentError("min is greater then or equal to max");

[floitsch, 2013/11/18 13:36:03]

Would be nice to have the values in the error message.

+    }
+    range = nextInt(range);

[floitsch, 2013/11/18 13:36:03]

I wouldn't have called the result of the random-call "range".

Either use a different variable, or just "return min + nextInt(range);".

+    return min + range;
+  }
+
   double nextDouble() {
     return ((nextInt(1 << 26) << 27) + nextInt(1 << 27)) / _POW2_53_D;
   }
 
   bool nextBool() {
     return nextInt(2) == 0;
   }
 
   // Constants used by the algorithm or masking.
   static const _MASK_32 = (1 << 32) - 1;
   static const _MASK_64 = (1 << 64) - 1;
   static const _POW2_32 = 1 << 32;
   static const _POW2_53_D = 1.0 * (1 << 53);
 
   static const _A = 0xffffda61;
 
   // Use a singleton Random object to get a new seed if no seed was passed.
   static var _prng = null;
 
   static int _nextSeed() {
     if (_prng == null) {
       // TODO(iposva): Use system to get a random seed.
       _prng = new Random(new Date.now().millisecondsSinceEpoch);
     }
     // Trigger the PRNG once to change the internal state.
     return _prng._nextInt32();
   }
 }