Fragment that establishes new BFC knows it's BFC offset in parent space

third_party/WebKit/Source/core/layout/ng/ng_constraint_space_builder.cc

Index: third_party/WebKit/Source/core/layout/ng/ng_constraint_space_builder.cc
diff --git a/third_party/WebKit/Source/core/layout/ng/ng_constraint_space_builder.cc b/third_party/WebKit/Source/core/layout/ng/ng_constraint_space_builder.cc
index 141a3d5da6ec335c285ef58a3e7ed52f6105582a..949178e1af96c65a9aee083be486ab5fb6e4f695 100644
--- a/third_party/WebKit/Source/core/layout/ng/ng_constraint_space_builder.cc
+++ b/third_party/WebKit/Source/core/layout/ng/ng_constraint_space_builder.cc
@@ -117,11 +117,18 @@ NGConstraintSpaceBuilder& NGConstraintSpaceBuilder::SetWritingMode(
 }
 
 NGConstraintSpace* NGConstraintSpaceBuilder::ToConstraintSpace() {
+  // Exclusions do not pass the formatting context boundary.
+  std::shared_ptr<NGExclusions> exclusions(
+      is_new_fc_ ? std::make_shared<NGExclusions>() : exclusions_);
+
   // Whether the child and the containing block are parallel to each other.
   // Example: vertical-rl and vertical-lr
   bool is_in_parallel_flow = (parent_writing_mode_ == kHorizontalTopBottom) ==
                              (writing_mode_ == kHorizontalTopBottom);
 
+  NGLogicalOffset bfc_offset = is_new_fc_ ? NGLogicalOffset() : bfc_offset_;
+  NGMarginStrut margin_strut = is_new_fc_ ? NGMarginStrut() : margin_strut_;
+
   if (is_in_parallel_flow) {
     return new NGConstraintSpace(
         static_cast<NGWritingMode>(writing_mode_),
@@ -134,7 +141,7 @@ NGConstraintSpace* NGConstraintSpaceBuilder::ToConstraintSpace() {
         is_inline_direction_triggers_scrollbar_,
         is_block_direction_triggers_scrollbar_,
         static_cast<NGFragmentationType>(fragmentation_type_), is_new_fc_,
-        margin_strut_, bfc_offset_, exclusions_);
+        margin_strut, bfc_offset, exclusions);
   }
 
   return new NGConstraintSpace(
@@ -148,7 +155,7 @@ NGConstraintSpace* NGConstraintSpaceBuilder::ToConstraintSpace() {
       is_block_direction_triggers_scrollbar_,
       is_inline_direction_triggers_scrollbar_,
       static_cast<NGFragmentationType>(fragmentation_type_), is_new_fc_,
-      margin_strut_, bfc_offset_, exclusions_);
+      margin_strut, bfc_offset, exclusions);
 }
 
 }  // namespace blink