[css-flexbox] More correctly implement percentage sizing

third_party/WebKit/Source/core/layout/LayoutFlexibleBox.h

Index: third_party/WebKit/Source/core/layout/LayoutFlexibleBox.h
diff --git a/third_party/WebKit/Source/core/layout/LayoutFlexibleBox.h b/third_party/WebKit/Source/core/layout/LayoutFlexibleBox.h
index 84b00869e4bbce763a4407b5189ba345181d4ba4..96b647f5898b4b15ec3a8465ddd5439b7d768f75 100644
--- a/third_party/WebKit/Source/core/layout/LayoutFlexibleBox.h
+++ b/third_party/WebKit/Source/core/layout/LayoutFlexibleBox.h
@@ -192,6 +192,11 @@ private:
     // This is used to cache the preferred size for orthogonal flow children so we don't have to relayout to get it
     HashMap<const LayoutObject*, LayoutUnit> m_intrinsicSizeAlongMainAxis;
 
+    // This set is used to keep track of which children we laid out in this current layout iteration.
+    // We need it because the ones in this set may need an additional layout pass for correct stretch alignment
+    // handling, as the first layout likely did not use the correct value for percentage sizing of children.
+    HashSet<const LayoutObject*> m_relaidOutChildren;
+
     mutable OrderIterator m_orderIterator;
     int m_numberOfInFlowChildrenOnFirstLine;
 };