Use xmlAtom / starAtom when possible instead of string literals

Source/core/timing/Performance.cpp

Index: Source/core/timing/Performance.cpp
diff --git a/Source/core/timing/Performance.cpp b/Source/core/timing/Performance.cpp
index 07a20310c3916a41411108d324c78d5f18b84e08..e441579b930df6dc43251b7f826effcfc1e855d6 100644
--- a/Source/core/timing/Performance.cpp
+++ b/Source/core/timing/Performance.cpp
@@ -171,7 +171,7 @@ static bool passesTimingAllowCheck(const ResourceResponse& response, Document* r
     if (timingAllowOriginString.isEmpty() || equalIgnoringCase(timingAllowOriginString, "null"))
         return false;
 
-    if (timingAllowOriginString == "*")
+    if (timingAllowOriginString == starAtom)
         return true;
 
     const String& securityOrigin = requestingDocument->securityOrigin()->toString();