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

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

Index: third_party/WebKit/Source/core/layout/LayoutTable.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutTable.cpp b/third_party/WebKit/Source/core/layout/LayoutTable.cpp
index 6d1bffb13fc7f102b76d0f737e0c55dc765ead2b..a9babf604e45a0e610eaf2e501aab4be93fc2b45 100644
--- a/third_party/WebKit/Source/core/layout/LayoutTable.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutTable.cpp
@@ -414,6 +414,19 @@ void LayoutTable::simplifiedNormalFlowLayout()
     }
 }
 
+bool LayoutTable::recalcChildOverflowAfterStyleChange()
+{
+    ASSERT(childNeedsOverflowRecalcAfterStyleChange());
+    clearChildNeedsOverflowRecalcAfterStyleChange();
+    bool childrenOverflowChanged = false;
+    for (LayoutTableSection* section = topSection(); section; section = sectionBelow(section)) {
+        if (!section->childNeedsOverflowRecalcAfterStyleChange())
+            continue;
+        childrenOverflowChanged |= section->recalcChildOverflowAfterStyleChange();
+    }
+    return childrenOverflowChanged;
+}
+
 void LayoutTable::layout()
 {
     ASSERT(needsLayout());