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 1a4eec73684beb0fbcb91cfc6ce9dcfbb60789b1..fc94812ce8330a6df3bb4a3ce7b51f5f955bd878 100644
--- a/third_party/WebKit/Source/core/layout/ng/ng_units.cc
+++ b/third_party/WebKit/Source/core/layout/ng/ng_units.cc
@@ -147,6 +147,16 @@ 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();
 }