[php] minor twek in anon objects

std/php/Boot.hx

@@ -911,9 +911,7 @@ private class HxAnon extends StdClass {
 
 	@:phpMagic
 	function __call( name:String, args:NativeArray ) : Dynamic {
-		var method = Syntax.field(this, name);
-		Syntax.keepVar(method);
-		return method(Syntax.splat(args));
+		return Syntax.code("($this->{0})(...{1})", name, args);
 	}
 }