Use initializer_lists for static WTF::HashSets.

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

Index: third_party/WebKit/Source/core/html/RelList.cpp
diff --git a/third_party/WebKit/Source/core/html/RelList.cpp b/third_party/WebKit/Source/core/html/RelList.cpp
index 3b4bd7d1227acbcbbf72e3128ecd72618fc78aac..a05e349c6f3c23545d03395e5c5487875aa25aa4 100644
--- a/third_party/WebKit/Source/core/html/RelList.cpp
+++ b/third_party/WebKit/Source/core/html/RelList.cpp
@@ -37,28 +37,31 @@ void RelList::setRelValues(const AtomicString& value)
     m_relValues.set(value, SpaceSplitString::ShouldNotFoldCase);
 }
 
-static RelList::SupportedTokens& supportedTokens()
+static HashSet<AtomicString>& supportedTokens()
 {
-    DEFINE_STATIC_LOCAL(RelList::SupportedTokens, supportedValuesMap, ());
-    if (supportedValuesMap.isEmpty()) {
-        supportedValuesMap.add("preload");
-        supportedValuesMap.add("preconnect");
-        supportedValuesMap.add("dns-prefetch");
-        supportedValuesMap.add("stylesheet");
-        supportedValuesMap.add("import");
-        supportedValuesMap.add("icon");
-        supportedValuesMap.add("alternate");
-        supportedValuesMap.add("prefetch");
-        supportedValuesMap.add("prerender");
-        supportedValuesMap.add("next");
-        supportedValuesMap.add("manifest");
-        supportedValuesMap.add("apple-touch-icon");
-        supportedValuesMap.add("apple-touch-icon-precomposed");
+    DEFINE_STATIC_LOCAL(HashSet<AtomicString>, tokens, ());
+
+    if (tokens.isEmpty()) {
+        tokens = {
+            "preload",
+            "preconnect",
+            "dns-prefetch",
+            "stylesheet",
+            "import",
+            "icon",
+            "alternate",
+            "prefetch",
+            "prerender",
+            "next",
+            "manifest",
+            "apple-touch-icon",
+            "apple-touch-icon-precomposed",
+        };
         if (RuntimeEnabledFeatures::linkServiceWorkerEnabled())
-            supportedValuesMap.add("serviceworker");
+            tokens.add("serviceworker");
     }
 
-    return supportedValuesMap;
+    return tokens;
 }
 
 bool RelList::validateTokenValue(const AtomicString& tokenValue, ExceptionState&) const