[LayoutNG] Add DHECK of CanUseInlineBox() in ContainerNode.cpp

ContainerNode::GetUpperLeftCorner() uses legacy inline structures, which
will be removed when LayoutNG is enabled. This patch adds a DCHECK to
ease the tracking of the conversion of existing usage of legacy inline
structures.

Bug: 591099
Change-Id: Idac4b13a590e9799affe1f5a34726ecc7f7f1bab
Reviewed-on: https://chromium-review.googlesource.com/769567
Commit-Queue: Xiaocheng Hu <xiaochengh@chromium.org>
Reviewed-by: Emil A Eklund <eae@chromium.org>
Cr-Commit-Position: refs/heads/master@{#516824}

third_party/WebKit/LayoutTests/TestExpectations

@@ -677,6 +677,9 @@ crbug.com/728378 virtual/layout_ng/overflow/overflow-position-003.html [ Failure
 
 # ====== LayoutNG,LayoutNGPaintFragments ======
 
+### Crash site: ContainerNode.cpp
+crbug.com/714962 virtual/layout_ng_paint/fast/inline/inline-with-empty-inline-children.html [ Crash ]
+
 ### Crash site: DrawingRecorder.cpp
 crbug.com/714962 virtual/layout_ng_paint/fast/inline/dirtyLinesForInline.html [ Crash ]
 crbug.com/714962 virtual/layout_ng_paint/fast/inline/drawStyledEmptyInlinesWithWS.html [ Crash Failure ]
@@ -728,7 +731,6 @@ crbug.com/714962 virtual/layout_ng_paint/fast/inline/drawStyledEmptyInlines.html
 crbug.com/714962 virtual/layout_ng_paint/fast/inline/inline-borders-with-bidi-override.html [ Failure ]
 crbug.com/714962 virtual/layout_ng_paint/fast/inline/inline-destroy-dirty-lines-crash.html [ Failure ]
 crbug.com/714962 virtual/layout_ng_paint/fast/inline/inline-focus-ring-under-absolute-enclosing-relative-div.html [ Failure ]
-crbug.com/714962 virtual/layout_ng_paint/fast/inline/inline-with-empty-inline-children.html [ Failure ]
 crbug.com/714962 virtual/layout_ng_paint/fast/inline/left-right-center-inline-alignment-in-ltr-and-rtl-blocks.html [ Failure ]
 crbug.com/714962 virtual/layout_ng_paint/fast/inline/out-of-flow-objects-and-whitespace-after-empty-inline.html [ Failure ]
 crbug.com/714962 virtual/layout_ng_paint/fast/inline/outline-continuations.html [ Failure ]

third_party/WebKit/Source/core/dom/ContainerNode.cpp

@@ -1019,6 +1019,7 @@ bool ContainerNode::GetUpperLeftCorner(FloatPoint& point) const {
       return true;
     }
 
+    DCHECK(CanUseInlineBox(*o));
     if (p->GetNode() && p->GetNode() == this && o->IsText() && !o->IsBR() &&
         !ToLayoutText(o)->HasTextBoxes()) {
       // Do nothing - skip unrendered whitespace that is a child or next sibling