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>

components/layout_2020/fragment_tree/base_fragment.rs

@@ -104,6 +104,10 @@ bitflags! {
         /// for empty table cells when 'empty-cells' is 'hide' and also table wrappers.  This flag
         /// doesn't avoid hit-testing nor does it prevent the painting outlines.
         const DO_NOT_PAINT = 1 << 6;
+        /// Whether or not the size of this fragment depends on the block size of its container
+        /// and the fragment can be a flex item. This flag is used to cache items during flex
+        /// layout.
+        const SIZE_DEPENDS_ON_BLOCK_CONSTRAINTS_AND_CAN_BE_CHILD_OF_FLEX_ITEM = 1 << 7;
     }
 }