Remove deprecation warning from using Haxe versions 4.2 or greater (w…

[TerryCavanagh]

…ithout breaking backwards compatibility)

I've been using Haxe 4.2.5 recently, and the biggest change is that the function Std.is has been renamed Std.isOfType, which causes lots of code to throw deprecation warnings. Crashdumper appears to work completely fine, except for this one case!

This solution seems to be the standard one, see e.g. Starling - https://github.com/openfl/starling/commit/f41cce244b78f38ac5c538f922427021ee949545