Avoid layout/full-repaint on view height change if possible

Source/core/rendering/RenderBlock.h

Index: Source/core/rendering/RenderBlock.h
diff --git a/Source/core/rendering/RenderBlock.h b/Source/core/rendering/RenderBlock.h
index f13b82510d33e128461027fd435de68d72e327c0..03060d8c1ae3ba6c27325c5aa73ef735f4cb2bdd 100644
--- a/Source/core/rendering/RenderBlock.h
+++ b/Source/core/rendering/RenderBlock.h
@@ -123,12 +123,18 @@ public:
 
     void addPercentHeightDescendant(RenderBox*);
     static void removePercentHeightDescendant(RenderBox*);
-    TrackedRendererListHashSet* percentHeightDescendants() const;
     static bool hasPercentHeightContainerMap();
     static bool hasPercentHeightDescendant(RenderBox*);
     static void clearPercentHeightDescendantsFrom(RenderBox*);
     static void removePercentHeightDescendantIfNeeded(RenderBox*);
 
+    TrackedRendererListHashSet* percentHeightDescendants() const;
+    bool hasPercentHeightDescendants() const
+    {
+        TrackedRendererListHashSet* descendants = percentHeightDescendants();
+        return descendants && !descendants->isEmpty();
+    }
+
     void setHasMarkupTruncation(bool b) { m_hasMarkupTruncation = b; }
     bool hasMarkupTruncation() const { return m_hasMarkupTruncation; }