Only add trailing border/padding to the right fragment.

We used to always subtract trailing border/padding for every fragment
that shouldn't have it, but this changed for table cells in CL:4303193.
To fix this, make sure that we only include trailing border/padding when
at the fragment that has the block-end edge of the box.

Bug: 1425075
Change-Id: Id7afa2eee764e1a8bb3017a90b212495278fe623
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4345873
Reviewed-by: Ian Kilpatrick <ikilpatrick@chromium.org>
Commit-Queue: Morten Stenshorne <mstensho@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1118245}

third_party/blink/renderer/core/layout/ng/ng_block_layout_algorithm.cc

@@ -876,14 +876,16 @@ const NGLayoutResult* NGBlockLayoutAlgorithm::FinishLayout(
         ExclusionSpace().ClearanceOffsetIncludingInitialLetter(EClear::kBoth));
   }
 
+  LayoutUnit block_end_border_padding = BorderScrollbarPadding().block_end;
+
   // If line clamping occurred, the intrinsic block-size comes from the
   // intrinsic block-size at the time of the clamp.
   if (intrinsic_block_size_when_clamped_) {
     DCHECK(container_builder_.BfcBlockOffset());
-    intrinsic_block_size_ = *intrinsic_block_size_when_clamped_ +
-                            BorderScrollbarPadding().block_end;
+    intrinsic_block_size_ =
+        *intrinsic_block_size_when_clamped_ + block_end_border_padding;
     end_margin_strut = NGMarginStrut();
-  } else if (BorderScrollbarPadding().block_end ||
+  } else if (block_end_border_padding ||
              previous_inflow_position->self_collapsing_child_had_clearance ||
              ConstraintSpace().IsNewFormattingContext()) {
     // The end margin strut of an in-flow fragment contributes to the size of
@@ -938,7 +940,15 @@ const NGLayoutResult* NGBlockLayoutAlgorithm::FinishLayout(
           previous_inflow_position->logical_block_offset + margin_strut_sum);
     }
 
-    intrinsic_block_size_ += BorderScrollbarPadding().block_end;
+    if ((BreakToken() && BreakToken()->IsAtBlockEnd()) ||
+        (container_builder_.HasInflowChildBreakInside() &&
+         !container_builder_.IsKnownToFitInFragmentainer())) {
+      // The block-end edge isn't in this fragment. We either haven't got there
+      // yet, or we're past it (and are overflowing). So don't add trailing
+      // border/padding.
+      block_end_border_padding = LayoutUnit();
+    }
+    intrinsic_block_size_ += block_end_border_padding;
     end_margin_strut = NGMarginStrut();
   } else {
     // Update our intrinsic block size to be just past the block-end border edge
@@ -1040,7 +1050,7 @@ const NGLayoutResult* NGBlockLayoutAlgorithm::FinishLayout(
   }
 
   if (UNLIKELY(InvolvedInBlockFragmentation(container_builder_))) {
-    NGBreakStatus status = FinalizeForFragmentation();
+    NGBreakStatus status = FinalizeForFragmentation(block_end_border_padding);
     if (status != NGBreakStatus::kContinue) {
       if (status == NGBreakStatus::kNeedsEarlierBreak)
         return container_builder_.Abort(NGLayoutResult::kNeedsEarlierBreak);
@@ -2386,7 +2396,8 @@ void NGBlockLayoutAlgorithm::ConsumeRemainingFragmentainerSpace(
   }
 }
 
-NGBreakStatus NGBlockLayoutAlgorithm::FinalizeForFragmentation() {
+NGBreakStatus NGBlockLayoutAlgorithm::FinalizeForFragmentation(
+    LayoutUnit block_end_border_padding_added) {
   if (Node().IsInlineFormattingContextRoot() && !early_break_ &&
       ConstraintSpace().HasBlockFragmentation()) {
     if (container_builder_.HasInflowChildBreakInside() ||
@@ -2428,7 +2439,7 @@ NGBreakStatus NGBlockLayoutAlgorithm::FinalizeForFragmentation() {
     space_left = FragmentainerSpaceLeft(ConstraintSpace());
 
   return FinishFragmentation(Node(), ConstraintSpace(),
-                             BorderPadding().block_end, space_left,
+                             block_end_border_padding_added, space_left,
                              &container_builder_);
 }
 

third_party/blink/renderer/core/layout/ng/ng_block_layout_algorithm.h

@@ -223,7 +223,8 @@ class CORE_EXPORT NGBlockLayoutAlgorithm
   // clipped box gets overflowed past the fragmentation line). The return value
   // can be checked for this. Only if kContinue is returned, can a fragment be
   // created.
-  NGBreakStatus FinalizeForFragmentation();
+  NGBreakStatus FinalizeForFragmentation(
+      LayoutUnit block_end_border_padding_added);
 
   // Insert a fragmentainer break before the child if necessary.
   // See |::blink::BreakBeforeChildIfNeeded()| for more documentation.

third_party/blink/web_tests/external/wpt/css/css-break/table/table-cell-border-001.html

@@ -0,0 +1,13 @@
+<!DOCTYPE html>
+<link rel="author" title="Morten Stenshorne" href="mailto:mstensho@chromium.org">
+<link rel="help" href="https://www.w3.org/TR/css-break-3/#box-splitting">
+<link rel="help" href="https://bugs.chromium.org/p/chromium/issues/detail?id=1425075">
+<link rel="match" href="../../reference/ref-filled-green-100px-square.xht">
+<p>Test passes if there is a filled green square and <strong>no red</strong>.</p>
+<div style="columns:2; gap:0; column-fill:auto; width:100px; height:100px; background:red;">
+  <div style="display:table; width:100%;">
+    <div style="display:table-cell; border-bottom:50px solid green; background:red;">
+      <div style="height:150px; background:green;"></div>
+    </div>
+  </div>
+</div>