[LayoutNG] Abort a layout once the BFC offset is resolved.

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

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef NGFragment_h
 #define NGFragment_h
 
 #include "core/CoreExport.h"
 #include "core/layout/ng/geometry/ng_logical_offset.h"
 #include "core/layout/ng/ng_physical_fragment.h"
@@ skipping 10 matching lines @@
 
  public:
   NGFragment(NGWritingMode writing_mode,
              const NGPhysicalFragment* physical_fragment)
       : physical_fragment_(physical_fragment), writing_mode_(writing_mode) {}
 
   NGWritingMode WritingMode() const {
     return static_cast<NGWritingMode>(writing_mode_);
   }
 
+  // TODO(ikilpatrick): Remove once block layout algorithm refactoring complete.
+  explicit operator bool() { return physical_fragment_ != nullptr; }
+
   // Returns the border-box size.
   LayoutUnit InlineSize() const;
   LayoutUnit BlockSize() const;
   NGLogicalSize Size() const;
 
   // Returns the offset relative to the parent fragment's content-box.
   LayoutUnit InlineOffset() const;
   LayoutUnit BlockOffset() const;
   NGLogicalOffset Offset() const;
 
   NGBorderEdges BorderEdges() const;
 
   NGPhysicalFragment::NGFragmentType Type() const;
 
  protected:
   const NGPhysicalFragment* physical_fragment_;
 
   unsigned writing_mode_ : 3;
 };
 
 }  // namespace blink
 
 #endif  // NGFragment_h