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

third_party/WebKit/Source/core/html/HTMLOptionsCollection.cpp

Index: third_party/WebKit/Source/core/html/HTMLOptionsCollection.cpp
diff --git a/third_party/WebKit/Source/core/html/HTMLOptionsCollection.cpp b/third_party/WebKit/Source/core/html/HTMLOptionsCollection.cpp
index 5445526758608a73ca6ec5ef28a9f8a734d59969..321ba136224e94b3caf940f5f29559c44789f8f1 100644
--- a/third_party/WebKit/Source/core/html/HTMLOptionsCollection.cpp
+++ b/third_party/WebKit/Source/core/html/HTMLOptionsCollection.cpp
@@ -53,14 +53,14 @@ void HTMLOptionsCollection::supportedPropertyNames(Vector<String>& names) {
     const AtomicString& idAttribute = element->getIdAttribute();
     if (!idAttribute.isEmpty()) {
       HashSet<AtomicString>::AddResult addResult =
-          existingNames.add(idAttribute);
+          existingNames.insert(idAttribute);
       if (addResult.isNewEntry)
         names.push_back(idAttribute);
     }
     const AtomicString& nameAttribute = element->getNameAttribute();
     if (!nameAttribute.isEmpty()) {
       HashSet<AtomicString>::AddResult addResult =
-          existingNames.add(nameAttribute);
+          existingNames.insert(nameAttribute);
       if (addResult.isNewEntry)
         names.push_back(nameAttribute);
     }