Remove int.pow and double.pow from VM library.

runtime/lib/double.dart

Index: runtime/lib/double.dart
diff --git a/runtime/lib/double.dart b/runtime/lib/double.dart
index 29247adb02c05c794bc74c09ba5d709fd5be3ce1..166d7311799a6c6b212dca67665727492b064c85 100644
--- a/runtime/lib/double.dart
+++ b/runtime/lib/double.dart
@@ -126,21 +126,6 @@ class _Double implements double {
   int toInt() native "Double_toInt";
   double toDouble() { return this; }
 
-  double pow(num exponent) {
-    if (exponent == 0) {
-      return 1.0;  // ECMA-262 15.8.2.13
-    }
-    if (exponent is! num) {
-      throw new ArgumentError(null);
-    }
-    double doubleExponent = exponent.toDouble();
-    if (isNaN || exponent.isNaN) {
-      return double.NAN;
-    }
-    return _pow(doubleExponent);
-  }
-  double _pow(double exponent) native "Double_pow";
-
   String toStringAsFixed(int fractionDigits) {
     // See ECMAScript-262, 15.7.4.5 for details.