Avoid layout when list color changes

Source/core/rendering/RenderListMarker.cpp

Index: Source/core/rendering/RenderListMarker.cpp
diff --git a/Source/core/rendering/RenderListMarker.cpp b/Source/core/rendering/RenderListMarker.cpp
index d30e6443e0b2c5e6865c63f3facffa333f286e2c..6b156ffa622fc2928d5ac4f33dfedd97e6cae25c 100644
--- a/Source/core/rendering/RenderListMarker.cpp
+++ b/Source/core/rendering/RenderListMarker.cpp
@@ -1633,4 +1633,19 @@ LayoutRect RenderListMarker::selectionRectForPaintInvalidation(const RenderLayer
     return rect;
 }
 
+void RenderListMarker::listItemStyleDidChange()
+{
+    RefPtr<RenderStyle> newStyle = RenderStyle::create();
+    // The marker always inherits from the list item, regardless of where it might end
+    // up (e.g., in some deeply nested line box). See CSS3 spec.
+    newStyle->inheritFrom(m_listItem->style());
+    if (style()) {
+        // Reuse the current margins otherwise resetting the margins to initial values

[mstensho (USE GERRIT), 2014/10/14 19:51:39]

Could you add something in front of "otherwise"? Either a semicolon or a full
stop, perhaps.

[Xianzhu, 2014/10/14 20:38:42]

Done.

+        // would trigger unnecessary layout.
+        newStyle->setMarginStart(style()->marginStart());
+        newStyle->setMarginEnd(style()->marginRight());
+    }
+    setStyle(newStyle.release());
+}
+
 } // namespace blink