layout: Don't consider a definite stretch size as intrinsic (#36045)

`block_size_is_zero_or_intrinsic()` was always returning true for
`stretch`. This function is used for the margin collapse heuristics
in block layout, so we were considering that an empty element with
`height: stretch` would self-collapse.

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

components/layout_2020/flow/mod.rs

@@ -2144,11 +2144,13 @@ impl<'container> PlacementState<'container> {
 
 fn block_size_is_zero_or_intrinsic(size: &StyleSize, containing_block: &ContainingBlock) -> bool {
     match size {
-        StyleSize::Auto |
-        StyleSize::MinContent |
-        StyleSize::MaxContent |
-        StyleSize::FitContent |
-        StyleSize::Stretch => true,
+        StyleSize::Auto | StyleSize::MinContent | StyleSize::MaxContent | StyleSize::FitContent => {
+            true
+        },
+        StyleSize::Stretch => {
+            // TODO: Should this return true when the containing block has a definite size of 0px?
+            !containing_block.size.block.is_definite()
+        },
         StyleSize::LengthPercentage(lp) => {
             // TODO: Should this resolve definite percentages? Blink does it, Gecko and WebKit don't.
             lp.is_definitely_zero() ||

tests/wpt/meta/css/css-sizing/stretch/block-height-009.html.ini

@@ -1,2 +0,0 @@
-[block-height-009.html]
-  expected: FAIL