Place the out of flow positioned blocks

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 f431434b207237f78a041a23472e9a776d166cb9..88ceb0aa6fcd2f9231fcc002da6e9ce55720baa0 100644
--- a/third_party/WebKit/Source/core/layout/ng/ng_units.cc
+++ b/third_party/WebKit/Source/core/layout/ng/ng_units.cc
@@ -142,6 +142,16 @@ NGPhysicalOffset& NGPhysicalOffset::operator+=(const NGPhysicalOffset& other) {
   return *this;
 }
 
+NGPhysicalOffset NGPhysicalOffset::operator-(
+    const NGPhysicalOffset& other) const {
+  return NGPhysicalOffset{this->left - other.left, this->top - other.top};
+}
+
+NGPhysicalOffset& NGPhysicalOffset::operator-=(const NGPhysicalOffset& other) {
+  *this = *this - other;
+  return *this;
+}
+
 bool NGBoxStrut::IsEmpty() const {
   return *this == NGBoxStrut();
 }