Avoid conditional branching on uninitialized values

C++ initializes members in the order in which they are defined in class. So the
order is important if the members are accessed by other initializers or methods
called from them.

Class BoxLayerWidget:
  _roundRect is initialized based on _layerType through the st() method.

Class Checkbox:
  Arguments of _text constructor depend on _checkAlignment through the
  countTextMinWidth and the checkRect methods.

ui/layers/box_layer_widget.h

@@ -128,6 +128,7 @@ class BoxLayerWidget : public LayerWidget, public BoxContentDelegate {
 
 	const style::Box *_st = nullptr;
 	not_null<LayerStackWidget*> _layer;
+	bool _layerType = false;
 	int _fullHeight = 0;
 
 	bool _noContentMargin = false;
@@ -140,7 +141,6 @@ class BoxLayerWidget : public LayerWidget, public BoxContentDelegate {
 	rpl::variable<QString> _additionalTitle;
 	int _titleLeft = 0;
 	int _titleTop = 0;
-	bool _layerType = false;
 	bool _closeByOutsideClick = true;
 
 	std::vector<object_ptr<RoundButton>> _buttons;

ui/widgets/checkbox.h

@@ -228,8 +228,8 @@ class Checkbox : public RippleButton {
 	rpl::event_stream<bool> _checkedChanges;
 	QPixmap _checkCache;
 
-	Text::String _text;
 	style::align _checkAlignment = style::al_left;
+	Text::String _text;
 	int _allowTextLines = 1;
 	bool _textBreakEverywhere = false;