Originally from https://github.com/HaxeFoundation/haxe/blob/a595b0406ca8d601ccec49044e76b3f91d487edd/std/js/html/Blob.hx used in http://haxe.io/releases/3.2.0/

Blob.hx

package js.html;

@:native("Blob")
extern class Blob
{
	var size(default,null) : Int;
	var type(default,null) : String;
	
	/** @throws DOMError */
	@:overload( function() : Void {} )
	function new( blobParts : Array<haxe.extern.EitherType<ArrayBuffer,haxe.extern.EitherType<ArrayBufferView,haxe.extern.EitherType<Blob,String>>>>, ?options : BlobPropertyBag ) : Void;
	/** @throws DOMError */
	function slice( ?start : Int, ?end : Int, ?contentType : String = "" ) : Blob;
}