Use Point2 consistently in Control methods

While Size2 and Point2 are just aliases,
which is why this doesn't fail compilation,
it's nice to have things consistent.

scene/gui/control.cpp

@@ -765,7 +765,7 @@ void Control::set_anchor_and_offset(Side p_side, real_t p_anchor, real_t p_pos,
 	set_offset(p_side, p_pos);
 }
 
-void Control::set_begin(const Size2 &p_point) {
+void Control::set_begin(const Point2 &p_point) {
 	ERR_FAIL_COND(!isfinite(p_point.x) || !isfinite(p_point.y));
 	if (data.offset[0] == p_point.x && data.offset[1] == p_point.y) {
 		return;
@@ -776,11 +776,11 @@ void Control::set_begin(const Size2 &p_point) {
 	_size_changed();
 }
 
-Size2 Control::get_begin() const {
-	return Size2(data.offset[0], data.offset[1]);
+Point2 Control::get_begin() const {
+	return Point2(data.offset[0], data.offset[1]);
 }
 
-void Control::set_end(const Size2 &p_point) {
+void Control::set_end(const Point2 &p_point) {
 	if (data.offset[2] == p_point.x && data.offset[3] == p_point.y) {
 		return;
 	}
@@ -790,8 +790,8 @@ void Control::set_end(const Size2 &p_point) {
 	_size_changed();
 }
 
-Size2 Control::get_end() const {
-	return Size2(data.offset[2], data.offset[3]);
+Point2 Control::get_end() const {
+	return Point2(data.offset[2], data.offset[3]);
 }
 
 void Control::set_h_grow_direction(GrowDirection p_direction) {
@@ -1358,11 +1358,11 @@ void Control::set_grow_direction_preset(LayoutPreset p_preset) {
 
 /// Manual positioning.
 
-void Control::_set_position(const Size2 &p_point) {
+void Control::_set_position(const Point2 &p_point) {
 	set_position(p_point);
 }
 
-void Control::set_position(const Size2 &p_point, bool p_keep_offsets) {
+void Control::set_position(const Point2 &p_point, bool p_keep_offsets) {
 	if (p_keep_offsets) {
 		_compute_anchors(Rect2(p_point, data.size_cache), data.offset, data.anchor);
 	} else {