Merge list of orthogonal writing mode roots into depth-ordered layout list.

third_party/WebKit/Source/core/frame/FrameView.cpp

Index: third_party/WebKit/Source/core/frame/FrameView.cpp
diff --git a/third_party/WebKit/Source/core/frame/FrameView.cpp b/third_party/WebKit/Source/core/frame/FrameView.cpp
index 9d353189efb8d043a67ef5c640bd8b363b04f933..28d4deb5bdb9f730452502c8e0fa40560ff7142a 100644
--- a/third_party/WebKit/Source/core/frame/FrameView.cpp
+++ b/third_party/WebKit/Source/core/frame/FrameView.cpp
@@ -1035,6 +1035,16 @@ void FrameView::performLayout(bool inSubtreeLayout) {
 
   ScriptForbiddenScope forbidScript;
 
+  if (inSubtreeLayout && hasOrthogonalWritingModeRoots()) {
+    // If we're going to lay out from each subtree root, rather than once from
+    // LayoutView, we need to merge the depth-ordered orthogonal writing mode
+    // root list into the depth-ordered list of subtrees scheduled for
+    // layout. Otherwise, during layout of one such subtree, we'd risk skipping
+    // over a subtree of objects needing layout.
+    DCHECK(!m_layoutSubtreeRootList.isEmpty());
+    scheduleOrthogonalWritingModeRootsForLayout();
+  }
+
   ASSERT(!isInPerformLayout());
   lifecycle().advanceTo(DocumentLifecycle::InPerformLayout);
 
@@ -1045,9 +1055,6 @@ void FrameView::performLayout(bool inSubtreeLayout) {
 
   forceLayoutParentViewIfNeeded();
 
-  if (hasOrthogonalWritingModeRoots())
-    layoutOrthogonalWritingModeRoots();
-
   if (inSubtreeLayout) {
     if (m_analyzer)
       m_analyzer->increment(LayoutAnalyzer::PerformLayoutRootLayoutObjects,
@@ -1065,6 +1072,8 @@ void FrameView::performLayout(bool inSubtreeLayout) {
     }
     m_layoutSubtreeRootList.clear();
   } else {
+    if (hasOrthogonalWritingModeRoots())
+      layoutOrthogonalWritingModeRoots();
     layoutFromRootObject(*layoutView());
   }
 
@@ -2124,17 +2133,28 @@ static inline void removeFloatingObjectsForSubtreeRoot(LayoutObject& root) {
   }
 }
 
+static bool prepareOrthogonalWritingModeRootForLayout(LayoutObject& root) {
+  DCHECK(root.isBox() && toLayoutBox(root).isOrthogonalWritingModeRoot());
+  if (!root.needsLayout() || root.isOutOfFlowPositioned() ||
+      root.isColumnSpanAll() ||
+      !root.styleRef().logicalHeight().isIntrinsicOrAuto())
+    return false;
+
+  removeFloatingObjectsForSubtreeRoot(root);
+  return true;
+}
+
 void FrameView::layoutOrthogonalWritingModeRoots() {
   for (auto& root : m_orthogonalWritingModeRootList.ordered()) {
-    ASSERT(root->isBox() && toLayoutBox(*root).isOrthogonalWritingModeRoot());
-    if (!root->needsLayout() || root->isOutOfFlowPositioned() ||
-        root->isColumnSpanAll() ||
-        !root->styleRef().logicalHeight().isIntrinsicOrAuto()) {
-      continue;
-    }
+    if (prepareOrthogonalWritingModeRootForLayout(*root))
+      layoutFromRootObject(*root);
+  }
+}
 
-    removeFloatingObjectsForSubtreeRoot(*root);
-    layoutFromRootObject(*root);
+void FrameView::scheduleOrthogonalWritingModeRootsForLayout() {
+  for (auto& root : m_orthogonalWritingModeRootList.ordered()) {
+    if (prepareOrthogonalWritingModeRootForLayout(*root))
+      m_layoutSubtreeRootList.add(*root);
   }
 }