[FragmentItem] Fix positions when the block is RTL

This patch fixes positions of line items when the block is
RTL.

Because the position of lines maybe decided after children
are positioned, this patch applies different transform to
children of lines from children of blocks.

This patch fixes ~250 failures.

Bug: 982194
Change-Id: I35871694ab2cd40f111fb3d338a67cdce2e0982e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1881006Reviewed-by: Yoshifumi Inoue <yosin@chromium.org>
Commit-Queue: Koji Ishii <kojii@chromium.org>
Cr-Commit-Position: refs/heads/master@{#709803}

third_party/blink/renderer/core/layout/ng/inline/ng_fragment_items_builder.cc

@@ -44,7 +44,7 @@ void NGFragmentItemsBuilder::AddLine(const NGPhysicalLineBoxFragment& line,
   // Add an empty item so that the start of the line can be set later.
   wtf_size_t line_start_index = items_.size();
   items_.Grow(line_start_index + 1);
-  offsets_.Grow(line_start_index + 1);
+  offsets_.push_back(offset);
 
   AddItems(current_line_.begin(), current_line_.end());
 
@@ -54,8 +54,8 @@ void NGFragmentItemsBuilder::AddLine(const NGPhysicalLineBoxFragment& line,
   // TODO(kojii): We probably need an end marker too for the reverse-order
   // traversals.
 
-  for (unsigned i = size_before; i < offsets_.size(); ++i)
-    offsets_[i] += offset;
+  // Keep children's offsets relative to |line|. They will be adjusted later in
+  // |ConvertToPhysical()|.
 
   current_line_.clear();
 #if DCHECK_IS_ON()
@@ -148,11 +148,37 @@ void NGFragmentItemsBuilder::ConvertToPhysical(WritingMode writing_mode,
   DCHECK(!is_converted_to_physical_);
 #endif
 
-  const LogicalOffset* offset_iter = offsets_.begin();
-  for (auto& item : items_) {
-    item->SetOffset(offset_iter->ConvertToPhysical(writing_mode, direction,
-                                                   outer_size, item->Size()));
-    ++offset_iter;
+  std::unique_ptr<NGFragmentItem>* item_iter = items_.begin();
+  const LogicalOffset* offset = offsets_.begin();
+  for (; item_iter != items_.end(); ++item_iter, ++offset) {
+    DCHECK_NE(offset, offsets_.end());
+    NGFragmentItem* item = item_iter->get();
+    item->SetOffset(offset->ConvertToPhysical(writing_mode, direction,
+                                              outer_size, item->Size()));
+
+    // Transform children of lines separately from children of the block,
+    // because they may have different directions from the block. To do
+    // this, their offsets are relative to their containing line box.
+    if (item->Type() == NGFragmentItem::kLine) {
+      unsigned descendants_count = item->DescendantsCount();
+      DCHECK(descendants_count);
+      if (descendants_count) {
+        const PhysicalRect line_box_bounds = item->Rect();
+        while (--descendants_count) {
+          ++offset;
+          ++item_iter;
+          DCHECK_NE(offset, offsets_.end());
+          DCHECK_NE(item_iter, items_.end());
+          item = item_iter->get();
+          // Use `kLtr` because inline items are after bidi-reoder, and that
+          // their offset is visual, not logical.
+          item->SetOffset(
+              offset->ConvertToPhysical(writing_mode, TextDirection::kLtr,
+                                        line_box_bounds.size, item->Size()) +
+              line_box_bounds.offset);
+        }
+      }
+    }
   }
 
 #if DCHECK_IS_ON()