[New Multicolumn] Support for block direction margins on spanners.

Source/core/rendering/RenderMultiColumnSpannerPlaceholder.cpp

Index: Source/core/rendering/RenderMultiColumnSpannerPlaceholder.cpp
diff --git a/Source/core/rendering/RenderMultiColumnSpannerPlaceholder.cpp b/Source/core/rendering/RenderMultiColumnSpannerPlaceholder.cpp
index b0555a5b2af6c9766a4a282382d2e39e16ee7c6e..f028dcf4b871ce38e4399eadaad1ad898b759ece 100644
--- a/Source/core/rendering/RenderMultiColumnSpannerPlaceholder.cpp
+++ b/Source/core/rendering/RenderMultiColumnSpannerPlaceholder.cpp
@@ -7,12 +7,23 @@
 
 namespace blink {
 
+static void copyMarginProperties(RenderStyle* placeholderStyle, const RenderStyle* spannerStyle)
+{
+    // We really only need the block direction margins, but there are no setters for that in
+    // RenderStyle. Just copy all margin sides. The inline ones don't matter anyway.
+    placeholderStyle->setMarginLeft(spannerStyle->marginLeft());
+    placeholderStyle->setMarginRight(spannerStyle->marginRight());
+    placeholderStyle->setMarginTop(spannerStyle->marginTop());
+    placeholderStyle->setMarginBottom(spannerStyle->marginBottom());
+}
+
 RenderMultiColumnSpannerPlaceholder* RenderMultiColumnSpannerPlaceholder::createAnonymous(RenderStyle* parentStyle, RenderBox* rendererInFlowThread)
 {
     RenderMultiColumnSpannerPlaceholder* newSpanner = new RenderMultiColumnSpannerPlaceholder(rendererInFlowThread);
     Document& document = rendererInFlowThread->document();
     newSpanner->setDocumentForAnonymous(&document);
     RefPtr<RenderStyle> newStyle = RenderStyle::createAnonymousStyleWithDisplay(parentStyle, BLOCK);
+    copyMarginProperties(newStyle.get(), rendererInFlowThread->style());
     newSpanner->setStyle(newStyle);
     return newSpanner;
 }
@@ -32,6 +43,13 @@ void RenderMultiColumnSpannerPlaceholder::spannerWillBeRemoved()
     // |this| should be destroyed by now.
 }
 
+void RenderMultiColumnSpannerPlaceholder::updateMarginProperties()
+{
+    RefPtr<RenderStyle> newStyle = RenderStyle::clone(style());
+    copyMarginProperties(newStyle.get(), m_rendererInFlowThread->style());
+    setStyle(newStyle);
+}
+
 void RenderMultiColumnSpannerPlaceholder::willBeRemovedFromTree()
 {
     if (m_rendererInFlowThread)
@@ -62,6 +80,8 @@ void RenderMultiColumnSpannerPlaceholder::computeLogicalHeight(LayoutUnit, Layou
 {
     computedValues.m_extent = m_rendererInFlowThread->logicalHeight();
     computedValues.m_position = logicalTop;
+    computedValues.m_margins.m_before = marginBefore();
+    computedValues.m_margins.m_after = marginAfter();
 }
 
 void RenderMultiColumnSpannerPlaceholder::invalidateTreeIfNeeded(const PaintInvalidationState& paintInvalidationState)