haxe.io.Bytes.getData(): BytesData != ArrayBuffer

Hi! I'm not sure if that is even an issue, but it took me a while to understand the difference between the Browser based implementation and the one used by node (electron). So I figured others might run into this very specific case as well:

In a nutshell this is the actual runtime difference: `Bytes.getData()` returns `ArrayBuffer` in the browser but `Buffer` in node (electron):
```haxe
// Browser:
haxe.io.Bytes.getData() : js.lib.ArrayBuffer
// Node (electron):
haxe.io.Bytes.getData() : js.node.Buffer
```

If you're interested - first the JavaScript runtime error I ran into:

```js
Uncaught (in promise) TypeError: Failed to execute 'decodeAudioData' on 'BaseAudioContext': parameter 1 is not of type 'ArrayBuffer'.
at AudioContextWaveformVc._onArrayBuffer (AudioContextWaveformVc.hx:126)
```

This is my little handler causing problems where _audioContext is an `AudioContext` instance:
```haxe
function _onArrayBuffer( arrayBuffer : ArrayBuffer ) {
_audioContext.decodeAudioData( arrayBuffer, _onDecodeAudioSuccess, _onDecodeAudioError );
}
```

This is my bytes receiving handler, which extracts the needed `ArrayBuffer` and forwards it:
```haxe
function _onBytes( data : Bytes ): Void {
var arrayBuffer : ArrayBuffer = data.getData();
_onArrayBuffer( arrayBuffer );
}
```

So if I use Google Chrome and Http to load the bytes it works fine:
```haxe
var http : Http = new Http( url );
http.onBytes = _onBytes;
http.request( true );
```

BUT if I use the File API to read the bytes, decoding audio throws the TypeError:
```haxe
var bytes : Bytes = File.getBytes( path );
_onBytes( bytes );
```

After some research I figured out, that running node (electron), `Bytes.getData()` actually returns a `js.node.Buffer` instance:

So in my case I had to convert the node buffer into an array buffer, which led me to this quite old stack overflow answer:
https://stackoverflow.com/questions/8609289/convert-a-binary-nodejs-buffer-to-javascript-arraybuffer/31394257#31394257

Just in case you need that:
```haxe
class BufferUtil {
public static function toArrayBuffer(buf:Buffer): ArrayBuffer {
var ab = new ArrayBuffer(buf.length);
var view = new Uint8Array(ab);
for (i in 0...buf.length) {
view[i] = buf[i];
}
return ab;
}
}
```

So is Bytes.getData() not consistent on all platforms?
Is this expected behaviour?
Or is this just a very rare edge case?