ceil/floor/truncate/round return integers.

runtime/lib/integers.dart

Index: runtime/lib/integers.dart
diff --git a/runtime/lib/integers.dart b/runtime/lib/integers.dart
index fa3bb8e5c511d1a453227d1b17c1524b0cb17706..8ee9dd35e416f4bda7460d56e0b280c2b487efb8 100644
--- a/runtime/lib/integers.dart
+++ b/runtime/lib/integers.dart
@@ -131,6 +131,11 @@ class _IntegerImplementation {
   int ceil() { return this; }
   int truncate() { return this; }
 
+  double roundToDouble() { return this.toDouble(); }
+  double floorToDouble() { return this.toDouble(); }
+  double ceilToDouble() { return this.toDouble(); }
+  double truncateToDouble() { return this.toDouble(); }
+
   num clamp(num lowerLimit, num upperLimit) {
     if (lowerLimit is! num) throw new ArgumentError(lowerLimit);
     if (upperLimit is! num) throw new ArgumentError(upperLimit);