Use Layout Opportunity Iterator to position new FC blocks.

third_party/WebKit/Source/core/layout/ng/ng_layout_algorithm.h

Index: third_party/WebKit/Source/core/layout/ng/ng_layout_algorithm.h
diff --git a/third_party/WebKit/Source/core/layout/ng/ng_layout_algorithm.h b/third_party/WebKit/Source/core/layout/ng/ng_layout_algorithm.h
index 231750602f6c817490ecca332435c35b1ba478d3..337eaff939bfea89e284999bde33561fd971688e 100644
--- a/third_party/WebKit/Source/core/layout/ng/ng_layout_algorithm.h
+++ b/third_party/WebKit/Source/core/layout/ng/ng_layout_algorithm.h
@@ -6,6 +6,7 @@
 #define NGLayoutAlgorithm_h
 
 #include "core/CoreExport.h"
+#include "core/layout/ng/ng_floats_utils.h"
 #include "core/layout/ng/ng_fragment_builder.h"
 #include "core/layout/ng/ng_min_max_content_size.h"
 #include "platform/wtf/Allocator.h"
@@ -64,6 +65,20 @@ class CORE_EXPORT NGLayoutAlgorithm {
     return container_builder_.BfcOffset().value();
   }
 
+#if defined(NGBlockLayoutAlgorithm_h) || defined(NGInlineLayoutAlgorithm_h)
+  // Positions pending floats starting from {@origin_block_offset} and relative
+  // to ContainerBfcOffset().
+  void PositionPendingFloats(LayoutUnit origin_block_offset) {
+    DCHECK(container_builder_.BfcOffset())
+        << "Parent BFC offset should be known here";
+    const auto& floating_objects = container_builder_.UnpositionedFloats();
+    PositionFloats(origin_block_offset, ContainerBfcOffset().block_offset,
+                   floating_objects, MutableConstraintSpace());
+    container_builder_.MutablePositionedFloats().AppendVector(floating_objects);
+    container_builder_.MutableUnpositionedFloats().Clear();
+  }
+#endif
+
   virtual NGInputNodeType* Node() const { return node_; }
 
   NGBreakTokenType* BreakToken() const { return break_token_; }