Optimize collapsed border calculation (step 2)

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

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "core/layout/LayoutTableBoxComponent.h"
 
 #include "core/layout/LayoutTable.h"
 #include "core/paint/ObjectPaintInvalidator.h"
 #include "core/style/ComputedStyle.h"
 
 namespace blink {
 
-void LayoutTableBoxComponent::InvalidateCollapsedBordersOnStyleChange(
+bool LayoutTableBoxComponent::NeedsInvalidateCollapsedBordersOnStyleChange(
     const LayoutObject& table_part,
-    LayoutTable& table,
+    const LayoutTable& table,
     const StyleDifference& diff,
     const ComputedStyle& old_style) {
   if (!table.CollapseBorders())
-    return;
-  if (old_style.Border() != table_part.StyleRef().Border() ||
-      (diff.TextDecorationOrColorChanged() &&
-       table_part.StyleRef().HasBorderColorReferencingCurrentColor()))
-    table.InvalidateCollapsedBorders();
+    return false;
+  return old_style.Border() != table_part.StyleRef().Border() ||
+         (diff.TextDecorationOrColorChanged() &&
+          table_part.StyleRef().HasBorderColorReferencingCurrentColor());
 }
 
 bool LayoutTableBoxComponent::DoCellsHaveDirtyWidth(
     const LayoutObject& table_part,
     const LayoutTable& table,
     const StyleDifference& diff,
     const ComputedStyle& old_style) {
   // ComputedStyle::diffNeedsFullLayoutAndPaintInvalidation sets needsFullLayout
   // when border sizes change: checking diff.needsFullLayout() is an
   // optimization, not required for correctness.
@@ skipping 20 matching lines @@
   auto& box = static_cast<LayoutTableBoxComponent&>(layout_object_);
   if (box.last_paint_result_ != kFullyPainted &&
       box.last_paint_rect_ != paint_rect)
     layout_object_.SetDisplayItemsUncached();
 
   box.last_paint_result_ = paint_result;
   box.last_paint_rect_ = paint_rect;
 }
 
 }  // namespace blink