[LayoutNG] Remove unnecessary #includes

third_party/WebKit/Source/core/layout/ng/ng_fragment_builder.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 NGFragmentBuilder_h
 #define NGFragmentBuilder_h
 
-#include "core/layout/ng/ng_fragment.h"
+#include "core/layout/ng/ng_physical_fragment_base.h"
 #include "core/layout/ng/ng_units.h"
 
 namespace blink {
 
+class NGFragmentBase;
+class NGPhysicalFragment;
+
 class CORE_EXPORT NGFragmentBuilder final
     : public GarbageCollectedFinalized<NGFragmentBuilder> {
  public:
   NGFragmentBuilder(NGPhysicalFragmentBase::NGFragmentType);
 
   using WeakBoxList = HeapLinkedHashSet<WeakMember<NGBlockNode>>;
 
   NGFragmentBuilder& SetWritingMode(NGWritingMode);
   NGFragmentBuilder& SetDirection(TextDirection);
 
@@ skipping 92 matching lines @@
   WeakBoxList out_of_flow_descendant_candidates_;
   Vector<OutOfFlowPlacement> out_of_flow_candidate_placements_;
 
   WeakBoxList out_of_flow_descendants_;
   Vector<NGStaticPosition> out_of_flow_positions_;
 };
 
 }  // namespace blink
 
 #endif  // NGFragmentBuilder