Don't always invalidate collapsed borders during table 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 8048a1b435da4df825f9d30d91250efce6231c3f..b5f782ce7e5ea2ea7db8a03b16dbb4fa1a97e6dc 100644
--- a/third_party/WebKit/Source/core/layout/LayoutTable.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutTable.cpp
@@ -102,8 +102,12 @@ void LayoutTable::StyleDidChange(StyleDifference diff,
   if (!old_style)
     return;
 
-  LayoutTableBoxComponent::InvalidateCollapsedBordersOnStyleChange(
-      *this, *this, diff, *old_style);
+  if (old_style->BorderCollapse() != StyleRef().BorderCollapse()) {
+    InvalidateCollapsedBorders();
+  } else {
+    LayoutTableBoxComponent::InvalidateCollapsedBordersOnStyleChange(
+        *this, *this, diff, *old_style);
+  }
 
   if (LayoutTableBoxComponent::DoCellsHaveDirtyWidth(*this, *this, diff,
                                                      *old_style))
@@ -756,9 +760,6 @@ void LayoutTable::UpdateLayout() {
 
     UpdateLayerTransformAfterLayout();
 
-    // Layout was changed, so probably borders too.
-    InvalidateCollapsedBorders();
-
     ComputeOverflow(ClientLogicalBottom());
     UpdateAfterLayout();
 
@@ -778,9 +779,6 @@ void LayoutTable::UpdateLayout() {
 
 void LayoutTable::InvalidateCollapsedBorders() {
   collapsed_borders_.clear();
-  if (!CollapseBorders())
-    return;
-
   collapsed_borders_valid_ = false;
   SetMayNeedPaintInvalidation();
 }