Self-collapsing block gets layout set during margin collapsing

Source/core/layout/LayoutBlockFlow.cpp

Index: Source/core/layout/LayoutBlockFlow.cpp
diff --git a/Source/core/layout/LayoutBlockFlow.cpp b/Source/core/layout/LayoutBlockFlow.cpp
index 1b07bd2e6254cef617e69ca710f4141f59067539..0f0156ca07bb95dd2b9eb28a4ef600c7462d5579 100644
--- a/Source/core/layout/LayoutBlockFlow.cpp
+++ b/Source/core/layout/LayoutBlockFlow.cpp
@@ -548,13 +548,16 @@ void LayoutBlockFlow::layoutBlockChild(LayoutBox& child, MarginInfo& marginInfo,
     // Cache if we are at the top of the block right now.
     bool atBeforeSideOfBlock = marginInfo.atBeforeSideOfBlock();
     bool childIsSelfCollapsing = child.isSelfCollapsingBlock();
+    bool childDiscardMarginBefore = mustDiscardMarginBeforeForChild(child);
+    bool childDiscardMarginAfter = mustDiscardMarginAfterForChild(child);
 
     // Now determine the correct ypos based off examination of collapsing margin
     // values.
-    LayoutUnit logicalTopBeforeClear = collapseMargins(child, marginInfo, childIsSelfCollapsing);
+    LayoutUnit logicalTopBeforeClear = collapseMargins(child, marginInfo, childIsSelfCollapsing, childDiscardMarginBefore, childDiscardMarginAfter);
 
     // Now check for clear.
-    LayoutUnit logicalTopAfterClear = clearFloatsIfNeeded(child, marginInfo, oldPosMarginBefore, oldNegMarginBefore, logicalTopBeforeClear, childIsSelfCollapsing);
+    bool childDiscardMargin = childDiscardMarginBefore || childDiscardMarginAfter;
+    LayoutUnit logicalTopAfterClear = clearFloatsIfNeeded(child, marginInfo, oldPosMarginBefore, oldNegMarginBefore, logicalTopBeforeClear, childIsSelfCollapsing, childDiscardMargin);
 
     bool paginated = view()->layoutState()->isPaginated();
     if (paginated) {
@@ -1116,11 +1119,8 @@ LayoutBlockFlow::MarginValues LayoutBlockFlow::marginValuesForChild(LayoutBox& c
     return LayoutBlockFlow::MarginValues(childBeforePositive, childBeforeNegative, childAfterPositive, childAfterNegative);
 }
 
-LayoutUnit LayoutBlockFlow::collapseMargins(LayoutBox& child, MarginInfo& marginInfo, bool childIsSelfCollapsing)
+LayoutUnit LayoutBlockFlow::collapseMargins(LayoutBox& child, MarginInfo& marginInfo, bool childIsSelfCollapsing, bool childDiscardMarginBefore, bool childDiscardMarginAfter)
 {
-    bool childDiscardMarginBefore = mustDiscardMarginBeforeForChild(child);
-    bool childDiscardMarginAfter = mustDiscardMarginAfterForChild(child);
-
     // The child discards the before margin when the the after margin has discard in the case of a self collapsing block.
     childDiscardMarginBefore = childDiscardMarginBefore || (childDiscardMarginAfter && childIsSelfCollapsing);
 
@@ -1298,7 +1298,7 @@ void LayoutBlockFlow::adjustPositionedBlock(LayoutBox& child, const MarginInfo&
         childLayer->setStaticBlockPosition(logicalTop);
 }
 
-LayoutUnit LayoutBlockFlow::clearFloatsIfNeeded(LayoutBox& child, MarginInfo& marginInfo, LayoutUnit oldTopPosMargin, LayoutUnit oldTopNegMargin, LayoutUnit yPos, bool childIsSelfCollapsing)
+LayoutUnit LayoutBlockFlow::clearFloatsIfNeeded(LayoutBox& child, MarginInfo& marginInfo, LayoutUnit oldTopPosMargin, LayoutUnit oldTopNegMargin, LayoutUnit yPos, bool childIsSelfCollapsing, bool childDiscardMargin)
 {
     LayoutUnit heightIncrease = getClearDelta(&child, yPos);
     marginInfo.setLastChildIsSelfCollapsingBlockWithClearance(false);
@@ -1308,7 +1308,6 @@ LayoutUnit LayoutBlockFlow::clearFloatsIfNeeded(LayoutBox& child, MarginInfo& ma
 
     if (childIsSelfCollapsing) {
         marginInfo.setLastChildIsSelfCollapsingBlockWithClearance(true);
-        bool childDiscardMargin = mustDiscardMarginBeforeForChild(child) || mustDiscardMarginAfterForChild(child);
         marginInfo.setDiscardMargin(childDiscardMargin);
 
         // For self-collapsing blocks that clear, they can still collapse their