ceil/floor/truncate/round return integers.

runtime/lib/double.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.
 
 class _Double implements double {
   factory _Double.fromInteger(int value)
       native "Double_doubleFromInteger";
   int get hashCode {
     if (isNaN || isInfinite) return 0;
     return toInt();
@@ skipping 82 matching lines @@
   bool get isNegative native "Double_getIsNegative";
   bool get isInfinite native "Double_getIsInfinite";
   bool get isNaN native "Double_getIsNaN";
 
   double abs() {
     // Handle negative 0.0.
     if (this == 0.0) return 0.0;
     return this < 0.0 ? -this : this;
   }
 
-  double round() native "Double_round";
-  double floor() native "Double_floor";
-  double ceil () native "Double_ceil";
-  double truncate() native "Double_truncate";
+  int round() => roundToDouble().toInt();
+  int floor() => floorToDouble().toInt();
+  int ceil () => ceilToDouble().toInt();
+  int truncate() => truncateToDouble().toInt();
+
+  double roundToDouble() native "Double_round";
+  double floorToDouble() native "Double_floor";
+  double ceilToDouble() native "Double_ceil";
+  double truncateToDouble() native "Double_truncate";
 
   num clamp(num lowerLimit, num upperLimit) {
     if (lowerLimit is! num) throw new ArgumentError(lowerLimit);
     if (upperLimit is! num) throw new ArgumentError(upperLimit);
 
     if (lowerLimit.compareTo(upperLimit) > 0) {
       throw new ArgumentError(lowerLimit);
     }
     if (lowerLimit.isNaN) return lowerLimit;
     if (this.compareTo(lowerLimit) < 0) return lowerLimit;
@@ skipping 119 matching lines @@
         return EQUAL;
       }
     } else if (isNaN) {
       return other.isNaN ? EQUAL : GREATER;
     } else {
       // Other is NaN.
       return LESS;
     }
   }
 }