Add a use counter to determine compat impact of changing flexbox's intrinsic size calculation

Source/core/layout/LayoutFlexibleBox.h

Index: Source/core/layout/LayoutFlexibleBox.h
diff --git a/Source/core/layout/LayoutFlexibleBox.h b/Source/core/layout/LayoutFlexibleBox.h
index 83588e2c679339432f8604addef1bca743a58634..69338c078e6ce88a5c070939e597dc1278656139 100644
--- a/Source/core/layout/LayoutFlexibleBox.h
+++ b/Source/core/layout/LayoutFlexibleBox.h
@@ -167,6 +167,8 @@ private:
     void flipForRightToLeftColumn();
     void flipForWrapReverse(const Vector<LineContext>&, LayoutUnit crossAxisStartEdge);
 
+    float countIntrinsicSizeForAlgorithmChange(LayoutUnit maxPreferredWidth, LayoutBox* child, float previousMaxContentFlexFraction) const;
+
     // 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;