CS of out-of-flow positioned objects should have is_new_fc == true

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 1974084634b56e33c59333b99bfbadad196081e4..5b39d9bfa5cbe81989974c9a1a67618070aab13a 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
@@ -22,7 +22,8 @@ NGConstraintSpaceBuilder::NGConstraintSpaceBuilder(
       is_inline_direction_triggers_scrollbar_(false),
       is_block_direction_triggers_scrollbar_(false),
       fragmentation_type_(parent_space->BlockFragmentationType()),
-      is_new_fc_(parent_space->IsNewFormattingContext()),
+      is_new_fc_(false),
+      is_parent_new_fc_(parent_space->IsNewFormattingContext()),
       is_anonymous_(false),
       text_direction_(static_cast<unsigned>(parent_space->Direction())),
       bfc_offset_(parent_space->bfc_offset_),
@@ -39,6 +40,7 @@ NGConstraintSpaceBuilder::NGConstraintSpaceBuilder(NGWritingMode writing_mode)
       is_block_direction_triggers_scrollbar_(false),
       fragmentation_type_(kFragmentNone),
       is_new_fc_(false),
+      is_parent_new_fc_(false),
       is_anonymous_(false),
       text_direction_(static_cast<unsigned>(TextDirection::kLtr)),
       exclusions_(new NGExclusions()) {}
@@ -175,8 +177,7 @@ RefPtr<NGConstraintSpace> NGConstraintSpaceBuilder::ToConstraintSpace(
 
   // Reset things that do not pass the Formatting Context boundary.
   std::shared_ptr<NGExclusions> exclusions(
-      is_new_fc_ ? std::make_shared<NGExclusions>() : exclusions_);
-  NGLogicalOffset bfc_offset = is_new_fc_ ? NGLogicalOffset() : bfc_offset_;
+      is_parent_new_fc_ ? std::make_shared<NGExclusions>() : exclusions_);

[ikilpatrick, 2017/03/23 16:39:59]

yeah i'm not sure that I understand this, exclusions are only relevant to a
block formatting context, they don't affect layout of a child's BFC if it
establishes one... e.g. even if you have an inner float which is large, it wont
avoid other floats in the parent BFC; for example:

https://software.hixie.ch/utilities/js/live-dom-viewer/?%3C!DOCTYPE%20html%3E...

I think the issues is that the layout opportunity iterator shouldn't be using
the available inline size? I.e. it should be using the resolved inline size of
the fragment? 

[Gleb Lanbin, 2017/03/24 20:10:05]

updated based on the offline discussion.

   NGMarginStrut margin_strut = is_new_fc_ ? NGMarginStrut() : margin_strut_;
   WTF::Optional<LayoutUnit> clearance_offset =
       is_new_fc_ ? WTF::nullopt : clearance_offset_;
@@ -191,7 +192,8 @@ RefPtr<NGConstraintSpace> NGConstraintSpaceBuilder::ToConstraintSpace(
         is_inline_direction_triggers_scrollbar_,
         is_block_direction_triggers_scrollbar_,
         static_cast<NGFragmentationType>(fragmentation_type_), is_new_fc_,
-        is_anonymous_, margin_strut, bfc_offset, exclusions, clearance_offset));
+        is_anonymous_, margin_strut, bfc_offset_, exclusions,
+        clearance_offset));
   }
   return adoptRef(new NGConstraintSpace(
       out_writing_mode, static_cast<TextDirection>(text_direction_),
@@ -201,7 +203,7 @@ RefPtr<NGConstraintSpace> NGConstraintSpaceBuilder::ToConstraintSpace(
       is_block_direction_triggers_scrollbar_,
       is_inline_direction_triggers_scrollbar_,
       static_cast<NGFragmentationType>(fragmentation_type_), is_new_fc_,
-      is_anonymous_, margin_strut, bfc_offset, exclusions, clearance_offset));
+      is_anonymous_, margin_strut, bfc_offset_, exclusions, clearance_offset));
 }
 
 }  // namespace blink