Make it clearer which state is mutable in block layout abspos impleme…

…ntation (#682)

src/compute/block.rs

@@ -340,13 +340,13 @@ fn perform_final_layout_on_in_flow_children(
 
  #[cfg_attr(not(feature = "content_size"), allow(unused_mut))]
  let mut inflow_content_size = Size::ZERO;
- let mut committed_offset = Point { x: resolved_content_box_inset.left, y: resolved_content_box_inset.top };
+ let mut committed_y_offset = resolved_content_box_inset.top;
  let mut first_child_top_margin_set = CollapsibleMarginSet::ZERO;
  let mut active_collapsible_margin_set = CollapsibleMarginSet::ZERO;
  let mut is_collapsing_with_first_margin_set = true;
  for item in items.iter_mut() {
  if item.position == Position::Absolute {
- item.static_position = committed_offset
+ item.static_position = Point { x: resolved_content_box_inset.left, y: committed_y_offset }
  } else {
  let item_margin = item.margin.map(|margin| margin.resolve_to_option(container_outer_width));
  let item_non_auto_margin = item_margin.map(|m| m.unwrap_or(0.0));
@@ -414,11 +414,11 @@ fn perform_final_layout_on_in_flow_children(
  item.can_be_collapsed_through = item_layout.margins_can_collapse_through;
  item.static_position = Point {
  x: resolved_content_box_inset.left,
- y: committed_offset.y + active_collapsible_margin_set.resolve(),
+ y: committed_y_offset + active_collapsible_margin_set.resolve(),
  };
  let location = Point {
  x: resolved_content_box_inset.left + inset_offset.x + resolved_margin.left,
- y: committed_offset.y + inset_offset.y + y_margin_offset,
+ y: committed_y_offset + inset_offset.y + y_margin_offset,
  };
 
  let scrollbar_size = Size {
@@ -469,7 +469,7 @@ fn perform_final_layout_on_in_flow_children(
  .collapse_with_set(top_margin_set)
  .collapse_with_set(bottom_margin_set);
  } else {
- committed_offset.y += item_layout.size.height + y_margin_offset;
+ committed_y_offset += item_layout.size.height + y_margin_offset;
  active_collapsible_margin_set = bottom_margin_set;
  }
  }
@@ -479,8 +479,8 @@ fn perform_final_layout_on_in_flow_children(
  let bottom_y_margin_offset =
  if own_margins_collapse_with_children.end { 0.0 } else { last_child_bottom_margin_set.resolve() };
 
- committed_offset.y += resolved_content_box_inset.bottom + bottom_y_margin_offset;
- let content_height = f32_max(0.0, committed_offset.y);
+ committed_y_offset += resolved_content_box_inset.bottom + bottom_y_margin_offset;
+ let content_height = f32_max(0.0, committed_y_offset);
  (inflow_content_size, content_height, first_child_top_margin_set, last_child_bottom_margin_set)
 }