Make LayoutObject::EnclosingBlockFlowFragment() strict

This patch changes |LayoutObject::EnclosingBlockFlowFragment()| to strict by
using |ChildrenInline()| instead of |HasNGInlineNodeData()| for detecting
failures of layout operation which doesn't compute inline node data.

Cq-Include-Trybots: master.tryserver.chromium.linux:linux_layout_tests_layout_ng
Bug: 714962
Change-Id: I14e724e06247c59e2f80a8a4db7dc1ef6e5433c7
Reviewed-on: https://chromium-review.googlesource.com/885542Reviewed-by: Koji Ishii <kojii@chromium.org>
Commit-Queue: Koji Ishii <kojii@chromium.org>
Cr-Commit-Position: refs/heads/master@{#531854}

third_party/WebKit/Source/core/layout/LayoutObject.cpp

@@ -746,7 +746,7 @@ LayoutBlockFlow* LayoutObject::EnclosingNGBlockFlow() const {
 const NGPhysicalBoxFragment* LayoutObject::EnclosingBlockFlowFragment() const {
   DCHECK(IsInline() || IsText());
   LayoutBlockFlow* const block_flow = EnclosingNGBlockFlow();
-  if (!block_flow || !block_flow->HasNGInlineNodeData())
+  if (!block_flow || !block_flow->ChildrenInline())
     return nullptr;
   // TODO(kojii): CurrentFragment isn't always available after layout clean.
   // Investigate why.