Adding or changing any of box-shadow, outline, or border-image-outset does not need a layout..

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

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Dirk Mueller (mueller@kde.org)
  *           (C) 2004 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2009 Google Inc. All rights reserved.
  * Copyright (C) 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  *
  * This library is free software; you can redistribute it and/or
@@ skipping 1905 matching lines @@
             // The following is for rect invalidation. For slimming paint v2, we can invalidate the rects
             // of the first line display item clients instead of the whole rect of the container.
             if (!RuntimeEnabledFeatures::slimmingPaintV2Enabled())
                 firstLineContainer->setShouldDoFullPaintInvalidation();
         }
     }
     if (diff.needsLayout())
         setNeedsLayoutAndPrefWidthsRecalc(LayoutInvalidationReason::StyleChange);
 }
 
-void LayoutObject::markContainingBlocksForOverflowRecalc()
+void LayoutObject::markAncestorsForOverflowRecalcIfNeeded()
 {
-    for (LayoutBlock* container = containingBlock(); container && !container->childNeedsOverflowRecalcAfterStyleChange(); container = container->containingBlock())
-        container->setChildNeedsOverflowRecalcAfterStyleChange();
+    LayoutObject* object = this;
+    do {
+        // Cell and row need to propagate the flag to their containing section and row as their containing block is the table wrapper.
+        // This enables us to only recompute overflow the modified sections / rows.
+        object = object->isTableCell() || object->isTableRow() ? object->parent() : object->containingBlock();
+        if (object)
+            object->setChildNeedsOverflowRecalcAfterStyleChange();
+    } while (object);
 }
 
 void LayoutObject::setNeedsOverflowRecalcAfterStyleChange()
 {
     bool neededRecalc = needsOverflowRecalcAfterStyleChange();
     setSelfNeedsOverflowRecalcAfterStyleChange();
     if (!neededRecalc)
-        markContainingBlocksForOverflowRecalc();
+        markAncestorsForOverflowRecalcIfNeeded();
 }
 
 void LayoutObject::setStyle(PassRefPtr<ComputedStyle> style)
 {
     ASSERT(style);
 
     if (m_style == style) {
         // We need to run through adjustStyleDifference() for iframes, plugins, and canvas so
         // style sharing is disabled for them. That should ensure that we never hit this code path.
         ASSERT(!isLayoutIFrame() && !isEmbeddedObject() && !isCanvas());
@@ skipping 49 matching lines @@
             setNeedsLayoutAndPrefWidthsRecalc(LayoutInvalidationReason::StyleChange);
         else if (updatedDiff.needsPositionedMovementLayout())
             setNeedsPositionedMovementLayout();
     }
 
     if (diff.transformChanged() && !needsLayout()) {
         if (LayoutBlock* container = containingBlock())
             container->setNeedsOverflowRecalcAfterStyleChange();
     }
 
+    if (diff.visualOverflowChanged() && !needsLayout()) {
+        if (isLayoutBlock())
+            setNeedsOverflowRecalcAfterStyleChange();
+        else
+            setNeedsLayoutAndPrefWidthsRecalc(LayoutInvalidationReason::StyleChange);

[Xianzhu, 2016/03/22 17:02:05]

Nit: please add a TODO here and reference bug 437012.

+    }
+
     if (diff.needsPaintInvalidationLayer() || updatedDiff.needsPaintInvalidationLayer())
         setShouldDoFullPaintInvalidationIncludingNonCompositingDescendants();
     else if (diff.needsPaintInvalidationObject() || updatedDiff.needsPaintInvalidationObject())
         setShouldDoFullPaintInvalidation();
 }
 
 void LayoutObject::styleWillChange(StyleDifference diff, const ComputedStyle& newStyle)
 {
     if (m_style) {
         // If our z-index changes value or our visibility changes,
@@ skipping 80 matching lines @@
         // If the object already needs layout, then setNeedsLayout won't do
         // any work. But if the containing block has changed, then we may need
         // to mark the new containing blocks for layout. The change that can
         // directly affect the containing block of this object is a change to
         // the position style.
         if (needsLayout() && oldStyle->position() != m_style->position())
             markContainerChainForLayout();
 
         // Ditto.
         if (needsOverflowRecalcAfterStyleChange() && oldStyle->position() != m_style->position())
-            markContainingBlocksForOverflowRecalc();
+            markAncestorsForOverflowRecalcIfNeeded();
 
         setNeedsLayoutAndPrefWidthsRecalc(LayoutInvalidationReason::StyleChange);
     } else if (diff.needsPositionedMovementLayout()) {
         setNeedsPositionedMovementLayout();
     }
 
     // Don't check for paint invalidation here; we need to wait until the layer has been
     // updated by subclasses before we know if we have to invalidate paints (in setStyle()).
 
     if (oldStyle && !areCursorsEqual(oldStyle, style())) {
@@ skipping 1609 matching lines @@
         const blink::LayoutObject* root = object1;
         while (root->parent())
             root = root->parent();
         root->showLayoutTreeAndMark(object1, "*", object2, "-", 0);
     } else {
         fprintf(stderr, "Cannot showLayoutTree. Root is (nil)\n");
     }
 }
 
 #endif