Revert "Add a counter for the number of LayoutNG-based LayoutObject instances"

This reverts commit c0b367bf.

Reason for revert: Found that this was an incorrect approach.

Original change's description:
> Add a counter for the number of LayoutNG-based LayoutObject instances
> 
> This CL has no user-visible behavior changes.
> 
> Note that LayoutNG ratio computed by this counter and |LocalFrameView::
> layout_object_counter_| is 55.1% on nytiimes.com.
> 
> Bug: 1067527
> Change-Id: I73e349a6f5daab79c5f4005ffc28997167f35788
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2136011
> Reviewed-by: Koji Ishii <kojii@chromium.org>
> Commit-Queue: Kent Tamura <tkent@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#756573}

TBR=yosin@chromium.org,tkent@chromium.org,kojii@chromium.org,ikilpatrick@chromium.org,mstensho@chromium.org

Change-Id: Ib534cb175a327ef6ee0bac05057bdd0b5dcb4d6f
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 1067527
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2137192Reviewed-by: Kent Tamura <tkent@chromium.org>
Commit-Queue: Kent Tamura <tkent@chromium.org>
Cr-Commit-Position: refs/heads/master@{#756601}

third_party/blink/renderer/core/frame/local_frame_view.h

@@ -387,7 +387,6 @@ class CORE_EXPORT LocalFrameView final
   bool InvalidateViewportConstrainedObjects();
 
   void IncrementLayoutObjectCount() { layout_object_counter_.Increment(); }
-  void IncrementLayoutObjectCountNG() { ++layout_object_counter_ng_; }
   void IncrementVisuallyNonEmptyCharacterCount(unsigned);
   void IncrementVisuallyNonEmptyPixelCount(const IntSize&);
   bool IsVisuallyNonEmpty() const { return is_visually_non_empty_; }
@@ -890,7 +889,6 @@ class CORE_EXPORT LocalFrameView final
   uint64_t visually_non_empty_pixel_count_;
   bool is_visually_non_empty_;
   LayoutObjectCounter layout_object_counter_;
-  uint32_t layout_object_counter_ng_;
 
   Member<FragmentAnchor> fragment_anchor_;
 

third_party/blink/renderer/core/layout/ng/layout_ng_mixin.cc

@@ -7,7 +7,6 @@
 #include <memory>
 #include <utility>
 
-#include "third_party/blink/renderer/core/frame/local_frame_view.h"
 #include "third_party/blink/renderer/core/layout/layout_view.h"
 #include "third_party/blink/renderer/core/layout/ng/layout_box_utils.h"
 #include "third_party/blink/renderer/core/layout/ng/ng_box_fragment_builder.h"
@@ -27,8 +26,6 @@ LayoutNGMixin<Base>::LayoutNGMixin(Element* element) : Base(element) {
       std::is_base_of<LayoutBlock, Base>::value,
       "Base class of LayoutNGMixin must be LayoutBlock or derived class.");
   DCHECK(!element || !element->ShouldForceLegacyLayout());
-  if (element)
-    Base::GetFrameView()->IncrementLayoutObjectCountNG();
 }
 
 template <typename Base>