[css-tables] Clean up code that detects significant border changes

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

Index: third_party/WebKit/Source/core/layout/LayoutTableBoxComponent.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutTableBoxComponent.cpp b/third_party/WebKit/Source/core/layout/LayoutTableBoxComponent.cpp
index b0ca3aaea220adc1d37963604f08dfeed2533c95..8c815b1a8ebdd6516ec19d907e4d3d93e017751b 100644
--- a/third_party/WebKit/Source/core/layout/LayoutTableBoxComponent.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutTableBoxComponent.cpp
@@ -4,6 +4,7 @@
 
 #include "core/layout/LayoutTableBoxComponent.h"
 
+#include "core/layout/LayoutTable.h"
 #include "core/style/ComputedStyle.h"
 
 namespace blink {
@@ -25,4 +26,13 @@ void LayoutTableBoxComponent::imageChanged(WrappedImagePtr, const IntRect*)
     m_backgroundChangedSinceLastPaintInvalidation = true;
 }
 
+bool LayoutTableBoxComponent::doCellsHaveDirtyWidth(const LayoutObject& tablePart, const LayoutTable& table, const StyleDifference& diff, const ComputedStyle& oldStyle)
+{
+    // ComputedStyle::diffNeedsFullLayoutAndPaintInvalidation sets needsFullLayout when border sizes
+    // change: checking diff.needsFullLayout() is an optimization, not required for correctness.
+    // TODO(dgrogan): Remove tablePart.needsLayout()? Perhaps it was an old optimization but now it
+    // seems that diff.needsFullLayout() implies tablePart.needsLayout().
+    return diff.needsFullLayout() && tablePart.needsLayout() && table.collapseBorders() && !oldStyle.border().sizeEquals(tablePart.style()->border());
+}
+
 } // namespace blink