Something wrong with Float64Array? in all targets but javascript?

This code yields different results on javascript and others targets.
It seem that other targets than javascript writes the same as a float32. Not sure why.

```
class Demo {
static private var _tempBytes = haxe.io.Bytes.alloc(8);
static private var _tempI8 = haxe.io.UInt8Array.fromBytes(_tempBytes);
static private var _tempF32 = haxe.io.Float32Array.fromBytes(_tempBytes);
static private var _tempI32 = haxe.io.Int32Array.fromBytes(_tempBytes);
static private var _tempF64 = haxe.io.Float64Array.fromBytes(_tempBytes);
static public function main() {
testF32();
testF64();
}
static private function testF32() {
trace('----');
_tempF32[0] = 1.0;
var i1 = _tempI32[1];
var i2 = _tempI32[0];
for (n in 0 ... 8) trace(_tempI8[n]);
trace('' + haxe.Int64.make(i1, i2)); // yields invalid value on PHP and Neko. Right value on nodejs
//trace(haxe.Int64.make(i1, i2)); // fails on javascript (Demo.hx:10: characters 2-7 : Cannot access private field toString)
}
static private function testF64() {
trace('----');
_tempF64[0] = 1.0;
var i1 = _tempI32[1];
var i2 = _tempI32[0];
for (n in 0 ... 8) trace(_tempI8[n]);
trace('' + haxe.Int64.make(i1, i2)); // yields invalid value on PHP and Neko. Right value on nodejs
//trace(haxe.Int64.make(i1, i2)); // fails on javascript (Demo.hx:10: characters 2-7 : Cannot access private field toString)
}
}
```