loadMapFromGraphic Fails On HTML5

• Haxe version: 4.1.5
• Flixel version: ?.?.?
• OpenFL version: ?.?.?
• Lime version: 7.7.0
• Affected target:
  HTML5

Code snippet reproducing the issue:

package;

import flixel.FlxState;

class PlayState extends FlxState
{
	override public function create():Void
	{
		super.create();
		var back = new FlxSprite();

		CoolFunctions.playSong('ikachan');
		CoolFunctions.fadeShit();

		bg = new FlxBackdrop("assets/images/Back.png");
		bg.scrollFactor.set(0.75, 0.75);
		add(bg);

		map.loadMapFromGraphic("assets/images/Map1.png", true, 1, [blank, a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, s, t], "assets/images/tileset.png", 16, 16, 0, 1, 0);
		map.useScaleHack = false;
		add(map);
	}
}

Observed behavior:

Expected behavior:

Reproduce the reported loadMapFromGraphic call from the issue's Haxe snippet with an HTML5 target, comparing the observed and expected screenshots. Start at the loadMapFromGraphic entry point and trace the HTML5 loading path; done means the map renders as expected in HTML5.