FlxPointer.getScreenPosition is returning impossible numbers

• Haxe version: 4.3.2
• Flixel version: 5.8.0
• OpenFL version: 9.3.3
• Lime version: 8.1.2
• Affected targets: html5, ?

Code snippet reproducing the issue:

package;

import flixel.FlxG;
import flixel.FlxState;

class PlayState extends FlxState
{
	override public function update(elapsed:Float)
	{
		super.update(elapsed);
		trace(FlxG.mouse.getScreenPosition());
	}
}

It's also useful to update openfl-content div's styling:

#openfl-content {
    background: #000000;
    width: 640px;
}

Observed behavior:

When placing the cursor at the top-left most position on the screen, trace(FlxG.mouse.getScreenPosition() is returning (x: 0 | y: -4)

Expected behavior:

When placing the cursor at the top-left most position on the screen, trace(FlxG.mouse.getScreenPosition() should return (x: 0 | y: 0)

Start at the FlxPointer.getScreenPosition entry point and reproduce the issue with the supplied HaxeFlixel, OpenFL, and Lime versions on the html5 target. Compare the returned coordinates at the top-left position; done means the result is (x: 0 | y: 0) rather than a negative y value.