Auto merge of #18462 - mrobinson:cleanup-building-state, r=emilio

Do some minor cleanups in display list building

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components/layout/inline.rs

@@ -9,6 +9,7 @@ use app_units::{Au, MIN_AU};
 use block::AbsoluteAssignBSizesTraversal;
 use context::LayoutContext;
 use display_list_builder::{DisplayListBuildState, InlineFlowDisplayListBuilding};
+use display_list_builder::StackingContextCollectionState;
 use euclid::{Point2D, Size2D};
 use floats::{FloatKind, Floats, PlacementInfo};
 use flow::{self, BaseFlow, Flow, FlowClass, ForceNonfloatedFlag};
@@ -1659,7 +1660,7 @@ impl Flow for InlineFlow {
 
     fn update_late_computed_block_position_if_necessary(&mut self, _: Au) {}
 
-    fn collect_stacking_contexts(&mut self, state: &mut DisplayListBuildState) {
+    fn collect_stacking_contexts(&mut self, state: &mut StackingContextCollectionState) {
         self.collect_stacking_contexts_for_inline(state);
     }