Remove DCHECKs from |PostLayout|

r790297 crrev.com/c/2309494 added comments saying the DCHECK
can hit, but forgot to remove it.

This patch removes it.

Bug: 1107204
Change-Id: I716e8faca243a7a9b8457c4acc2bb43cd8d33dfe
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2309877
Commit-Queue: Kent Tamura <tkent@chromium.org>
Auto-Submit: Koji Ishii <kojii@chromium.org>
Reviewed-by: Kent Tamura <tkent@chromium.org>
Cr-Commit-Position: refs/heads/master@{#790601}

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

@@ -358,7 +358,7 @@ const NGPhysicalFragment* NGPhysicalFragment::PostLayout() const {
   if (UNLIKELY(!layout_box))
     return nullptr;
   const wtf_size_t fragment_count = layout_box->PhysicalFragmentCount();
-  if (fragment_count == 0) {
+  if (UNLIKELY(fragment_count == 0)) {
     // This should not happen, but DCHECK hits. crbug.com/1107204
     return nullptr;
   }
@@ -369,7 +369,6 @@ const NGPhysicalFragment* NGPhysicalFragment::PostLayout() const {
     if (UNLIKELY(post_layout && post_layout != this)) {
       // This can happen at the relayout boundary crbug.com/829028
       // but DCHECKing |IsRelayoutBoundary| hits. crbug.com/1107204
-      DCHECK(layout_box->IsRelayoutBoundary());
       return post_layout;
     }
   }