layout: Avoid layout sometimes when stretching (#33967)

This is the second flexbox caching change. It seeks to detect when a
relayout can be avoided in the case of a stretching flex item. This
heuristic can be combined, because currently we still do relayout
sometimes when we do not need to.

For instance currently we always relayout when a flex child is itself a
column flex. This only needs to happen when the grandchildren themselves
grow or shrink. That optimization is perhaps a lower priority as
`flex-grow: 0 / flex-shrink: 1` is the default behavior for flex.

Since this change means we more consistenly zero out the percentage part
of `calc` expressions when they have circular dependencies, this causes one
test to start failing (`/css/css-values/calc-min-height-block-1.html`).
This is related to w3c/csswg-drafts#10969, which is pending on further
discussion in the working group.

Signed-off-by: Martin Robinson <mrobinson@igalia.com>
Co-authored-by: Oriol Brufau <obrufau@igalia.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/components/layout_2020/flexbox/construct.rs b/components/layout_2020/flexbox/construct.rs
index d1d3580aace..c4c5ff57d60 100644
--- a/components/layout_2020/flexbox/construct.rs
+++ b/components/layout_2020/flexbox/construct.rs
@@ -181,7 +181,7 @@ where
                         independent_formatting_context: IndependentFormattingContext::NonReplaced(
                             non_replaced,
                         ),
-                        cached_layout: Default::default(),
+                        block_content_size_cache: Default::default(),
                     })))
                 },
                 FlexLevelJob::Element {
@@ -213,7 +213,7 @@ where
                                 contents,
                                 self.text_decoration_line,
                             ),
-                            cached_layout: Default::default(),
+                            block_content_size_cache: Default::default(),
                         }))
                     };
                     box_slot.set(LayoutBox::FlexLevel(box_.clone()));