layout: Add a query for getting the effective overflow of an element and use it in script (#42251)

In layout calculation within script, Instead of relying on the computed
values for overflow, query the overflow from layout for its used value
to accurately reflect whether an element establish a scroll container.
This query will be used for `IntersectionObserver` as well.

Testing: There are new `IntersectionObserver` WPT failures:
- `intersection-observer/isIntersecting-change-events.html`
- `intersection-observer/containing-block.html`

The failures are more than likely a false positive because intersection
observation steps wasn't supposed to trigger a reflow, but it was
before. It could be caused by the implementation of
`IntersectionObserver` in major UAs being a little bit different from
the spec in the calculation of `threshold` and `isIntersecting` .

---------

Signed-off-by: Jo Steven Novaryo <steven.novaryo@gmail.com>
Signed-off-by: Martin Robinson <mrobinson@igalia.com>
Co-authored-by: Martin Robinson <mrobinson@igalia.com>

components/script/dom/window.rs

@@ -55,11 +55,12 @@ use js::rust::{
     MutableHandleValue,
 };
 use layout_api::{
-    BoxAreaType, CSSPixelRectIterator, ElementsFromPointFlags, ElementsFromPointResult,
-    FragmentType, Layout, LayoutImageDestination, PendingImage, PendingImageState,
-    PendingRasterizationImage, PhysicalSides, QueryMsg, ReflowGoal, ReflowPhasesRun, ReflowRequest,
-    ReflowRequestRestyle, ReflowStatistics, RestyleReason, ScrollContainerQueryFlags,
-    ScrollContainerResponse, TrustedNodeAddress, combine_id_with_fragment_type,
+    AxesOverflow, BoxAreaType, CSSPixelRectIterator, ElementsFromPointFlags,
+    ElementsFromPointResult, FragmentType, Layout, LayoutImageDestination, PendingImage,
+    PendingImageState, PendingRasterizationImage, PhysicalSides, QueryMsg, ReflowGoal,
+    ReflowPhasesRun, ReflowRequest, ReflowRequestRestyle, ReflowStatistics, RestyleReason,
+    ScrollContainerQueryFlags, ScrollContainerResponse, TrustedNodeAddress,
+    combine_id_with_fragment_type,
 };
 use malloc_size_of::MallocSizeOf;
 use media::WindowGLContext;
@@ -3023,6 +3024,20 @@ impl Window {
         self.layout().query_elements_from_point(point, flags)
     }
 
+    pub(crate) fn query_effective_overflow(&self, node: &Node) -> Option<AxesOverflow> {
+        self.layout_reflow(QueryMsg::EffectiveOverflow);
+        self.query_effective_overflow_without_reflow(node)
+    }
+
+    pub(crate) fn query_effective_overflow_without_reflow(
+        &self,
+        node: &Node,
+    ) -> Option<AxesOverflow> {
+        self.layout
+            .borrow()
+            .query_effective_overflow(node.to_trusted_node_address())
+    }
+
     pub(crate) fn hit_test_from_input_event(
         &self,
         input_event: &ConstellationInputEvent,