Make leading OOF objects to be handled by block layout in LayoutNG

third_party/WebKit/Source/core/layout/LayoutBlockFlow.cpp

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 2968 matching lines @@
     AddChildBeforeDescendant(new_child, before_child);
     return;
   }
 
   bool made_boxes_non_inline = false;
 
   // A block has to either have all of its children inline, or all of its
   // children as blocks.
   // So, if our children are currently inline and a block child has to be
   // inserted, we move all our inline children into anonymous block boxes.
-  bool child_is_block_level =
-      !new_child->IsInline() && !new_child->IsFloatingOrOutOfFlowPositioned();
+  bool child_is_block_level = !new_child->IsInline();
+
+  // ** LayoutNG **
+  // We want to use the block layout for out of flow positioned
+  // objects when they go in front of inline blocks or if they are just
+  // standalone objects.
+  // Example 1:
+  //   <div id="zero"><div id="oof"></div></div>
+  //   Legacy Layout: #oof is in inline context.
+  //   LayoutNG: #oof is in block context.
+  //
+  // Example 2:
+  //   <div id=container><oof></oof>Hello!</div>
+  //   Legacy Layout: oof is in inline context.
+  //   LayoutNG: oof is in block context.
+  //
+  // Example 3:
+  //   <div id=container>Hello!<oof></oof></div>
+  //   Legacy Layout: oof is in inline context.
+  //   LayoutNG: oof is in inline context.
+  bool layout_ng_enabled = RuntimeEnabledFeatures::layoutNGEnabled();
+  if (new_child->IsFloatingOrOutOfFlowPositioned())
+    child_is_block_level = layout_ng_enabled && !FirstChild();
+
   if (ChildrenInline()) {
     if (child_is_block_level) {
       // Wrap the inline content in anonymous blocks, to allow for the new block
       // child to be inserted.
       MakeChildrenNonInline(before_child);
       made_boxes_non_inline = true;
 
       if (before_child && before_child->Parent() != this) {
         before_child = before_child->Parent();
         DCHECK(before_child->IsAnonymousBlock());
@@ skipping 13 matching lines @@
     if (after_child && after_child->IsAnonymousBlock()) {
       after_child->AddChild(new_child);
       return;
     }
 
     if (new_child->IsInline()) {
       // No suitable existing anonymous box - create a new one.
       LayoutBlockFlow* new_block = ToLayoutBlockFlow(CreateAnonymousBlock());
       LayoutBox::AddChild(new_block, before_child);
       // Reparent adjacent floating or out-of-flow siblings to the new box.
-      new_block->ReparentPrecedingFloatingOrOutOfFlowSiblings();
+      if (!layout_ng_enabled)
+        new_block->ReparentPrecedingFloatingOrOutOfFlowSiblings();
       new_block->AddChild(new_child);
       new_block->ReparentSubsequentFloatingOrOutOfFlowSiblings();
       return;
     }
   }
 
   // Skip the LayoutBlock override, since that one deals with anonymous child
   // insertion in a way that isn't sufficient for us, and can only cause trouble
   // at this point.
   LayoutBox::AddChild(new_child, before_child);
@@ skipping 1634 matching lines @@
   return LayoutBlock::DeprecatedInvalidatePaint(paint_invalidation_state);
 }
 
 void LayoutBlockFlow::InvalidateDisplayItemClients(
     PaintInvalidationReason invalidation_reason) const {
   BlockFlowPaintInvalidator(*this).InvalidateDisplayItemClients(
       invalidation_reason);
 }
 
 }  // namespace blink