layout: Respect alignment when sizing replaced abspos (#35085)

If an absolutely position element which is replaced has `justify-self`
or `align-self` set to `stretch`, and no inset is `auto` on that axis,
then an automatic size should behave as `stretch`, not as `fit-content`.

Signed-off-by: Oriol Brufau <obrufau@igalia.com>

components/layout_2020/geom.rs

@@ -68,7 +68,23 @@ impl<T: Default> Default for LogicalVec2<T> {
     }
 }
 
+impl<T: Copy> From<T> for LogicalVec2<T> {
+    fn from(value: T) -> Self {
+        Self {
+            inline: value,
+            block: value,
+        }
+    }
+}
+
 impl<T> LogicalVec2<T> {
+    pub(crate) fn as_ref(&self) -> LogicalVec2<&T> {
+        LogicalVec2 {
+            inline: &self.inline,
+            block: &self.block,
+        }
+    }
+
     pub fn map_inline_and_block_axes<U>(
         &self,
         inline_f: impl FnOnce(&T) -> U,