[LayoutNG] WIP on storing layout output in the legacy tree for multicol.

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

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 4226 matching lines @@
       UseCounter::count(document(), UseCounter::CSSOverflowPaged);
       return LayoutPagedFlowThread::createAnonymous(document(), styleRef());
     default:
       NOTREACHED();
       return nullptr;
   }
 }
 
 void LayoutBlockFlow::createOrDestroyMultiColumnFlowThreadIfNeeded(
     const ComputedStyle* oldStyle) {
-  if (RuntimeEnabledFeatures::layoutNGEnabled())
-    return;
-
   // Paged overflow trumps multicol in this implementation. Ideally, it should
   // be possible to have both paged overflow and multicol on the same element,
   // but then we need two flow threads. Anyway, this is nothing to worry about
   // until we can actually nest multicol properly inside other fragmentation
   // contexts.
   FlowThreadType type = getFlowThreadType(styleRef());
 
   if (multiColumnFlowThread()) {
     ASSERT(oldStyle);
     if (type != getFlowThreadType(*oldStyle)) {
@@ skipping 342 matching lines @@
   return LayoutBlock::invalidatePaintIfNeeded(paintInvalidationState);
 }
 
 void LayoutBlockFlow::invalidateDisplayItemClients(
     PaintInvalidationReason invalidationReason) const {
   BlockFlowPaintInvalidator(*this).invalidateDisplayItemClients(
       invalidationReason);
 }
 
 }  // namespace blink