Do not collapse margins with padding/border b/w parent and first/last child

third_party/WebKit/Source/core/layout/ng/ng_units.cc

Index: third_party/WebKit/Source/core/layout/ng/ng_units.cc
diff --git a/third_party/WebKit/Source/core/layout/ng/ng_units.cc b/third_party/WebKit/Source/core/layout/ng/ng_units.cc
index 4f45a68dcab327a8166c123a649c9dae56847d6a..d65adf7c2a8d0fb29454d3f645e6952a4a783772 100644
--- a/third_party/WebKit/Source/core/layout/ng/ng_units.cc
+++ b/third_party/WebKit/Source/core/layout/ng/ng_units.cc
@@ -79,6 +79,14 @@ void NGMarginStrut::AppendMarginBlockEnd(const LayoutUnit& value) {
   }
 }
 
+void NGMarginStrut::SetMarginBlockStart(const LayoutUnit& value) {
+  if (value < 0) {
+    negative_margin_block_start = value;
+  } else {
+    margin_block_start = value;
+  }
+}
+
 void NGMarginStrut::SetMarginBlockEnd(const LayoutUnit& value) {
   if (value < 0) {
     negative_margin_block_end = value;
@@ -88,10 +96,10 @@ void NGMarginStrut::SetMarginBlockEnd(const LayoutUnit& value) {
 }
 
 String NGMarginStrut::ToString() const {
-  return String::format(
-      "Start: (%d %d) End: (%d %d)", negative_margin_block_start.toInt(),
-      margin_block_start.toInt(), negative_margin_block_end.toInt(),
-      margin_block_end.toInt());
+  return String::format("Start: (%d %d) End: (%d %d)",
+                        margin_block_start.toInt(), margin_block_end.toInt(),
+                        negative_margin_block_start.toInt(),
+                        negative_margin_block_end.toInt());
 }
 
 bool NGMarginStrut::operator==(const NGMarginStrut& other) const {