AS3/TS ExternsGenerator incorrectly generate public var for default read-only properties

[pngdrift]

Describe the bug
Fields declared in Haxe as public var type(default, null):String are incorrectly generated as public var in AS3/TS externs, instead of being accessible only via getter.

To Reproduce
Steps to reproduce the behavior:

1. Run this Royale sample

package {
  import openfl.display.Bitmap;
  import openfl.display.BitmapData;
  import openfl.display.Sprite;
  import openfl.ui.Keyboard;
  import openfl.ui.Multitouch;

  public class App extends Sprite {

    public function App() {
      super();
      var bitmapData:BitmapData = new BitmapData(32,32,false,0xFF0000);
      bitmapData.perlinNoise(2,2,2,2,true,false);

      /* Every line below should produce read-only property errors */
      bitmapData.width = 111;
      bitmapData.height = 55;
      parent = new Sprite();
      Multitouch.maxTouchPoints = 99;
      Keyboard.capsLock = true;
      /* end */

      addChild(new Bitmap(bitmapData));
      trace(parent);
      trace(Multitouch.maxTouchPoints);
      trace(Keyboard.capsLock);
    }
  }
}

2. Observe that compilation succeeds instead of producing errors.

Expected behavior
Errors should be shown: Property _x_ is read-only.

OpenFL Targets
AS3 Royale, TypeScript

Additional context
I think the problem is here

openfl-js/scripts/AS3ExternsGenerator.hx

Line 445 in ebba70e

var isAccessor = read == AccCall || write == AccCall || mustBeAccessor(classField.name, interfaces);

openfl-js/scripts/TSExternsGenerator.hx

Line 493 in ebba70e

var isAccessor = read == AccCall || write == AccCall || mustBeAccessor(classField.name, interfaces);

I tried changing the line to:

var isAccessor = read == AccCall || write == AccCall || mustBeAccessor(classField.name, interfaces)
					|| (read != write && (read == AccNormal  || write == AccNormal));

This seems fixes the issue, but then in ByteArray, length property is generated as getter instead of public var. I’m not sure why.

[joshtynjala]

default is not a getter in Haxe, though. It is a simple field in Haxe. get is used for a getter in Haxe.

I think that TypeScript has a readonly modifier, though, so maybe that could be used. However, AS3 doesn't really have the concept of a read-only field. There's const, but I'd say that's subtly different.