Migrate WTF::HashSet::add() to ::insert() [part 1 of N]

third_party/WebKit/Source/core/dom/custom/CustomElementUpgradeSorter.cpp

Index: third_party/WebKit/Source/core/dom/custom/CustomElementUpgradeSorter.cpp
diff --git a/third_party/WebKit/Source/core/dom/custom/CustomElementUpgradeSorter.cpp b/third_party/WebKit/Source/core/dom/custom/CustomElementUpgradeSorter.cpp
index e915e92425bdbd6d7a55322d29fd3f551491fef6..93d6e26d4ebb732c1ba21c88830adeb18d122a6c 100644
--- a/third_party/WebKit/Source/core/dom/custom/CustomElementUpgradeSorter.cpp
+++ b/third_party/WebKit/Source/core/dom/custom/CustomElementUpgradeSorter.cpp
@@ -28,19 +28,19 @@ CustomElementUpgradeSorter::AddResult
 CustomElementUpgradeSorter::addToParentChildMap(Node* parent, Node* child) {
   ParentChildMap::AddResult result = m_parentChildMap->add(parent, nullptr);
   if (!result.isNewEntry) {
-    result.storedValue->value->add(child);
+    result.storedValue->value->insert(child);
     // The entry for the parent exists; so must its parents.
     return kParentAlreadyExistsInMap;
   }
 
   ChildSet* childSet = new ChildSet();
-  childSet->add(child);
+  childSet->insert(child);
   result.storedValue->value = childSet;
   return kParentAddedToMap;
 }
 
 void CustomElementUpgradeSorter::add(Element* element) {
-  m_elements->add(element);
+  m_elements->insert(element);
 
   for (Node *n = element, *parent = n->parentOrShadowHostNode(); parent;
        n = parent, parent = parent->parentOrShadowHostNode()) {