[css-tables] Mark sibling cells dirty when a cell is added

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

Index: third_party/WebKit/Source/core/layout/LayoutTableRow.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutTableRow.cpp b/third_party/WebKit/Source/core/layout/LayoutTableRow.cpp
index 39bdbe41f383311d058cea2b39f8bacc7c4cd6db..e51a52a501388e39453a156c45bffff9e99fd5d9 100644
--- a/third_party/WebKit/Source/core/layout/LayoutTableRow.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutTableRow.cpp
@@ -153,8 +153,17 @@ void LayoutTableRow::addChild(LayoutObject* child, LayoutObject* beforeChild)
     LayoutTableBoxComponent::addChild(cell, beforeChild);
 
     // Generated content can result in us having a null section so make sure to null check our parent.
-    if (parent())
+    if (parent()) {
         section()->addCell(cell, this);
+        // When borders collapse, adding a cell can affect the the width of neighboring cells.
+        LayoutTable* enclosingTable = table();
+        if (enclosingTable && enclosingTable->collapseBorders()) {
+            if (LayoutTableCell* previousCell = cell->previousCell())
+                previousCell->setNeedsLayoutAndPrefWidthsRecalc(LayoutInvalidationReason::TableChanged);
+            if (LayoutTableCell* nextCell = cell->nextCell())
+                nextCell->setNeedsLayoutAndPrefWidthsRecalc(LayoutInvalidationReason::TableChanged);
+        }
+    }
 
     if (beforeChild || nextRow())
         section()->setNeedsCellRecalc();