Fix for 1267: Implement (partially) Math.pow for integers.

runtime/lib/integers.dart

Index: runtime/lib/integers.dart
===================================================================
--- runtime/lib/integers.dart	(revision 4405)
+++ runtime/lib/integers.dart	(working copy)
@@ -118,7 +118,12 @@
   double toDouble() { return new Double.fromInteger(this); }
 
   int pow(int exponent) {
-    throw "IntegerImplementation.pow not implemented";
+    double res = this.toDouble().pow(exponent);

[siva, 2012/02/22 01:10:43]

our Bigint to double conversion is not implemented correctly and I am not sure
this would work for that case. Maybe instead you could throw an unimplemented
exception if 'this' is a bigint.

[srdjan, 2012/02/22 01:38:59]

Done.

+    if (res.isInfinite()) {
+      // Use Bigint instead.
+      throw "IntegerImplementation.pow not implemented for large integers.";
+    }
+    return res.toInt();
   }
 
   String toStringAsFixed(int fractionDigits) {