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

third_party/WebKit/Source/core/dom/CSSSelectorWatch.cpp

Index: third_party/WebKit/Source/core/dom/CSSSelectorWatch.cpp
diff --git a/third_party/WebKit/Source/core/dom/CSSSelectorWatch.cpp b/third_party/WebKit/Source/core/dom/CSSSelectorWatch.cpp
index bd1ff5f126b00b792c9c44bc5a8c6895b360893d..a5f42bc3b17726e6b157ddf5a78b6b2ca5453bfd 100644
--- a/third_party/WebKit/Source/core/dom/CSSSelectorWatch.cpp
+++ b/third_party/WebKit/Source/core/dom/CSSSelectorWatch.cpp
@@ -104,7 +104,7 @@ void CSSSelectorWatch::updateSelectorMatches(
     if (it != m_addedSelectors.end())
       m_addedSelectors.remove(it);
     else
-      m_removedSelectors.add(selector);
+      m_removedSelectors.insert(selector);
   }
 
   for (const auto& selector : addedSelectors) {
@@ -118,7 +118,7 @@ void CSSSelectorWatch::updateSelectorMatches(
     if (it != m_removedSelectors.end())
       m_removedSelectors.remove(it);
     else
-      m_addedSelectors.add(selector);
+      m_addedSelectors.insert(selector);
   }
 
   if (!shouldUpdateTimer)