tor-browser

commit a038c8d2a8355610aa4de7daf2af98d77a4fecd2
parent 968a602d3cf2ee54f5b564c53694139d07693789
Author: Cristina Horotan <chorotan@mozilla.com>
Date:   Fri,  9 Jan 2026 19:14:09 +0200

Revert "Bug 2009424 - Make containing block adjustment work for default anchored frames. r=layout-anchor-positioning-reviewers,layout-reviewers,dshin" for causing wpt failures on anchor-scroll-position-try-006.html

This reverts commit d8bd94aa646aa77a24a487be85480a479341d8eb.

Diffstat:
M
layout/generic/AbsoluteContainingBlock.cpp
 | 
29
++++++++++++++---------------
A
testing/web-platform/meta/css/css-anchor-position/anchor-scroll-position-try-007.html.ini
 | 
5
+++++

2 files changed, 19 insertions(+), 15 deletions(-)
diff --git a/layout/generic/AbsoluteContainingBlock.cpp b/layout/generic/AbsoluteContainingBlock.cpp
@@ -1326,7 +1326,6 @@ void AbsoluteContainingBlock::ReflowAbsoluteFrame(
       // The current containing block, with ongoing modifications.
       // Starts as a local containing block.
       nsRect containingBlock = aOriginalContainingBlockRect;
-      nsRect scrollableContainingBlock = aOriginalScrollableContainingBlockRect;
       const auto defaultAnchorInfo = [&]() -> Maybe<AnchorPosInfo> {
         if (!aAnchorPosResolutionCache) {
           return Nothing{};
@@ -1342,18 +1341,6 @@ void AbsoluteContainingBlock::ReflowAbsoluteFrame(
         containingBlock = aOriginalScrollableContainingBlockRect;
       }
 
-      if (ViewportFrame* viewport = do_QueryFrame(aDelegatingFrame)) {
-        if (IsSnapshotContainingBlock(aKidFrame)) {
-          return ContainingBlockRect{
-              dom::ViewTransition::SnapshotContainingBlockRect(
-                  viewport->PresContext())};
-        }
-        MOZ_ASSERT(aOriginalScrollableContainingBlockRect ==
-                   aOriginalContainingBlockRect);
-        containingBlock = scrollableContainingBlock =
-            viewport->GetContainingBlockAdjustedForScrollbars(aReflowInput);
-      }
-
       // https://drafts.csswg.org/css-position/#original-cb
       // Handle grid-based adjustment first...
       if (isGrid) {
@@ -1395,12 +1382,24 @@ void AbsoluteContainingBlock::ReflowAbsoluteFrame(
           aAnchorPosResolutionCache->mReferenceData->mScrollCompensatedSides =
               GetScrollCompensatedSidesFor(resolvedPositionArea);
           return ContainingBlockRect{
-              offset, resolvedPositionArea, scrollableContainingBlock,
+              offset, resolvedPositionArea,
+              aOriginalScrollableContainingBlockRect,
               // Unscroll the CB by canceling out the previously applied
               // scroll offset (See above), the offset will be applied later.
               scrolledAnchorCb + offset};
         }
-        return ContainingBlockRect{scrollableContainingBlock, containingBlock};
+        return ContainingBlockRect{aOriginalScrollableContainingBlockRect,
+                                   containingBlock};
+      }
+
+      if (ViewportFrame* viewport = do_QueryFrame(aDelegatingFrame)) {
+        if (!IsSnapshotContainingBlock(aKidFrame)) {
+          return ContainingBlockRect{
+              viewport->GetContainingBlockAdjustedForScrollbars(aReflowInput)};
+        }
+        return ContainingBlockRect{
+            dom::ViewTransition::SnapshotContainingBlockRect(
+                viewport->PresContext())};
       }
       return ContainingBlockRect{containingBlock};
     }();
diff --git a/testing/web-platform/meta/css/css-anchor-position/anchor-scroll-position-try-007.html.ini b/testing/web-platform/meta/css/css-anchor-position/anchor-scroll-position-try-007.html.ini
@@ -0,0 +1,5 @@
+[anchor-scroll-position-try-007.html]
+  [Should use the third position option with enough space left]
+    expected:
+      if os == "android": PASS
+      FAIL