Don't let a column spanner affect the self-margin-collapsing state of the parent.

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

Index: third_party/WebKit/Source/core/layout/LayoutBlockFlow.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutBlockFlow.cpp b/third_party/WebKit/Source/core/layout/LayoutBlockFlow.cpp
index c633ed2fc07dfc64fb31b29b623f75520fd98366..5f19e9846581bf878384cbc3ec1381d4178425ce 100644
--- a/third_party/WebKit/Source/core/layout/LayoutBlockFlow.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutBlockFlow.cpp
@@ -424,11 +424,10 @@ bool LayoutBlockFlow::checkIfIsSelfCollapsingBlock() const {
       return !firstLineBox();
 
     // Whether or not we collapse is dependent on whether all our normal flow
-    // children
-    // are also self-collapsing.
+    // children are also self-collapsing.
     for (LayoutBox* child = firstChildBox(); child;
          child = child->nextSiblingBox()) {
-      if (child->isFloatingOrOutOfFlowPositioned())
+      if (child->isFloatingOrOutOfFlowPositioned() || child->isColumnSpanAll())
         continue;
       if (!child->isSelfCollapsingBlock())
         return false;