Style changes to visual overflow do not require a layout

Source/core/rendering/style/RenderStyle.cpp

Index: Source/core/rendering/style/RenderStyle.cpp
diff --git a/Source/core/rendering/style/RenderStyle.cpp b/Source/core/rendering/style/RenderStyle.cpp
index b28acc9e5e761b018b9edd720c32b41aa2c3e093..4f875ad5ca4190c0011198add9e4d02855d1d57d 100644
--- a/Source/core/rendering/style/RenderStyle.cpp
+++ b/Source/core/rendering/style/RenderStyle.cpp
@@ -469,10 +469,6 @@ bool RenderStyle::diffNeedsFullLayoutAndPaintInvalidation(const RenderStyle& oth
             && *rareNonInheritedData->m_flexibleBox.get() != *other.rareNonInheritedData->m_flexibleBox.get())
             return true;
 
-        // FIXME: We should add an optimized form of layout that just recomputes visual overflow.
-        if (!rareNonInheritedData->shadowDataEquivalent(*other.rareNonInheritedData.get()))
-            return true;
-
         if (!rareNonInheritedData->reflectionDataEquivalent(*other.rareNonInheritedData.get()))
             return true;
 
@@ -588,11 +584,6 @@ bool RenderStyle::diffNeedsFullLayoutAndPaintInvalidation(const RenderStyle& oth
     if ((visibility() == COLLAPSE) != (other.visibility() == COLLAPSE))
         return true;
 
-    if (!m_background->outline().visuallyEqual(other.m_background->outline())) {
-        // FIXME: We only really need to recompute the overflow but we don't have an optimized layout for it.
-        return true;
-    }
-
     // Movement of non-static-positioned object is special cased in RenderStyle::visualInvalidationDiff().
 
     return false;
@@ -656,6 +647,9 @@ bool RenderStyle::diffNeedsPaintInvalidationLayer(const RenderStyle& other) cons
 
 bool RenderStyle::diffNeedsPaintInvalidationObject(const RenderStyle& other) const
 {
+    if (!m_background->outline().visuallyEqual(other.m_background->outline()))
+        return true;
+
     if (inherited_flags._visibility != other.inherited_flags._visibility
         || inherited_flags.m_printColorAdjust != other.inherited_flags.m_printColorAdjust
         || inherited_flags._insideLink != other.inherited_flags._insideLink
@@ -674,6 +668,7 @@ bool RenderStyle::diffNeedsPaintInvalidationObject(const RenderStyle& other) con
         if (rareNonInheritedData->userDrag != other.rareNonInheritedData->userDrag
             || rareNonInheritedData->m_objectFit != other.rareNonInheritedData->m_objectFit
             || rareNonInheritedData->m_objectPosition != other.rareNonInheritedData->m_objectPosition
+            || !rareNonInheritedData->shadowDataEquivalent(*other.rareNonInheritedData.get())
             || !dataEquivalent(rareNonInheritedData->m_shapeOutside, other.rareNonInheritedData->m_shapeOutside)
             || !dataEquivalent(rareNonInheritedData->m_clipPath, other.rareNonInheritedData->m_clipPath))
             return true;
@@ -697,8 +692,14 @@ void RenderStyle::updatePropertySpecificDifferences(const RenderStyle& other, St
 
         if (rareNonInheritedData->m_filter != other.rareNonInheritedData->m_filter)
             diff.setFilterChanged();
+
+        if (!rareNonInheritedData->shadowDataEquivalent(*other.rareNonInheritedData.get()))
+            diff.setVisualOverflowChanged();
     }
 
+    if (!m_background->outline().visuallyEqual(other.m_background->outline()) || !surround->border.visualOverflowEqual(other.surround->border))
+        diff.setVisualOverflowChanged();
+
     if (!diff.needsPaintInvalidation()) {
         if (inherited->color != other.inherited->color
             || inherited_flags.m_textUnderline != other.inherited_flags.m_textUnderline