Reapply CL "Option to truncate integers to 64 bits, part 2"

runtime/lib/isolate.cc

Index: runtime/lib/isolate.cc
diff --git a/runtime/lib/isolate.cc b/runtime/lib/isolate.cc
index d9ea131e9423bd0790e036950f9b90737c5662e6..1bf00b28f78cd364e7b7da17b9a3c0a48727f34b 100644
--- a/runtime/lib/isolate.cc
+++ b/runtime/lib/isolate.cc
@@ -70,7 +70,7 @@ DEFINE_NATIVE_ENTRY(RawReceivePortImpl_factory, 1) {
 
 DEFINE_NATIVE_ENTRY(RawReceivePortImpl_get_id, 1) {
   GET_NON_NULL_NATIVE_ARGUMENT(ReceivePort, port, arguments->NativeArgAt(0));
-  return Integer::NewFromUint64(port.Id());
+  return Integer::New(port.Id());
 }
 
 DEFINE_NATIVE_ENTRY(RawReceivePortImpl_get_sendport, 1) {
@@ -82,12 +82,12 @@ DEFINE_NATIVE_ENTRY(RawReceivePortImpl_closeInternal, 1) {
   GET_NON_NULL_NATIVE_ARGUMENT(ReceivePort, port, arguments->NativeArgAt(0));
   Dart_Port id = port.Id();
   PortMap::ClosePort(id);
-  return Integer::NewFromUint64(id);
+  return Integer::New(id);
 }
 
 DEFINE_NATIVE_ENTRY(SendPortImpl_get_id, 1) {
   GET_NON_NULL_NATIVE_ARGUMENT(SendPort, port, arguments->NativeArgAt(0));
-  return Integer::NewFromUint64(port.Id());
+  return Integer::New(port.Id());
 }
 
 DEFINE_NATIVE_ENTRY(SendPortImpl_get_hashcode, 1) {