Make ~/, round, ceil, floor, truncate return ints. Remove toInt.

runtime/lib/double.dart

Index: runtime/lib/double.dart
diff --git a/runtime/lib/double.dart b/runtime/lib/double.dart
index 8d4699180f2c45d116f8c54a17822dc6f5863ba5..ec2f9765f9baa8df4ab737c7ac2768d68b6fbf34 100644
--- a/runtime/lib/double.dart
+++ b/runtime/lib/double.dart
@@ -7,7 +7,7 @@ class _Double implements double {
       native "Double_doubleFromInteger";
   int get hashCode {
     try {
-      return toInt();
+      return truncate();
     } on FormatException catch (e) {
       return 0;
     }
@@ -27,10 +27,10 @@ class _Double implements double {
   }
   double _mul(double other) native "Double_mul";
 
-  double operator ~/(num other) {
+  int operator ~/(num other) {
     return _trunc_div(other.toDouble());
   }
-  double _trunc_div(double other) native "Double_trunc_div";
+  int _trunc_div(double other) native "Double_trunc_div";
 
   double operator /(num other) {
     return _div(other.toDouble());
@@ -81,7 +81,7 @@ class _Double implements double {
   double _mulFromInteger(int other) {
     return new _Double.fromInteger(other) * this;
   }
-  double _truncDivFromInteger(int other) {
+  int _truncDivFromInteger(int other) {
     return new _Double.fromInteger(other) ~/ this;
   }
   double _moduloFromInteger(int other) {
@@ -103,10 +103,10 @@ class _Double implements double {
     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() native "Double_round";
+  int floor() native "Double_floor";
+  int ceil () native "Double_ceil";
+  int truncate() native "Double_truncate";
 
   num clamp(num lowerLimit, num upperLimit) {
     if (lowerLimit is! num) throw new ArgumentError(lowerLimit);
@@ -121,7 +121,6 @@ class _Double implements double {
     return this;
   }
 
-  int toInt() native "Double_toInt";
   double toDouble() { return this; }
 
   double pow(num exponent) {