Be more restrictive about forcing relayout of children for pagination.

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

Index: third_party/WebKit/Source/core/layout/LayoutFlexibleBox.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutFlexibleBox.cpp b/third_party/WebKit/Source/core/layout/LayoutFlexibleBox.cpp
index 6cd1c691060730a91390c7439312311586390714..cd826f62a4705ba0ad974dfdee5492ac511b185e 100644
--- a/third_party/WebKit/Source/core/layout/LayoutFlexibleBox.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutFlexibleBox.cpp
@@ -32,6 +32,7 @@
 
 #include "core/frame/UseCounter.h"
 #include "core/layout/LayoutState.h"
+#include "core/layout/LayoutView.h"
 #include "core/layout/TextAutosizer.h"
 #include "core/paint/BlockPainter.h"
 #include "core/paint/PaintLayer.h"
@@ -1859,6 +1860,7 @@ void LayoutFlexibleBox::layoutAndPlaceChildren(
   LayoutUnit maxAscent, maxDescent;  // Used when align-items: baseline.
   LayoutUnit maxChildCrossAxisExtent;
   bool shouldFlipMainAxis = !isColumnFlow() && !isLeftToRightFlow();
+  bool isPaginated = view()->layoutState()->isPaginated();
   for (size_t i = 0; i < children.size(); ++i) {
     const FlexItem& flexItem = children[i];
     LayoutBox* child = flexItem.box;
@@ -1940,6 +1942,9 @@ void LayoutFlexibleBox::layoutAndPlaceChildren(
 
     mainAxisOffset += justifyContentSpaceBetweenChildren(
         availableFreeSpace, distribution, children.size());
+
+    if (isPaginated)
+      updateFragmentationInfoForChild(*child);
   }
 
   if (isColumnFlow())