Make DocumentLoader::timing return a reference

Source/core/timing/PerformanceNavigation.cpp

Index: Source/core/timing/PerformanceNavigation.cpp
diff --git a/Source/core/timing/PerformanceNavigation.cpp b/Source/core/timing/PerformanceNavigation.cpp
index c1735ceeff5fedca5ada03606a38d8d0e8f96d67..e50ef4261393f5ee979764e2578ff5e311a9d805 100644
--- a/Source/core/timing/PerformanceNavigation.cpp
+++ b/Source/core/timing/PerformanceNavigation.cpp
@@ -70,11 +70,11 @@ unsigned short PerformanceNavigation::redirectCount() const
     if (!loader)
         return 0;
 
-    DocumentLoadTiming* timing = loader->timing();
-    if (timing->hasCrossOriginRedirect())
+    const DocumentLoadTiming& timing = loader->timing();
+    if (timing.hasCrossOriginRedirect())
         return 0;
 
-    return timing->redirectCount();
+    return timing.redirectCount();
 }
 
 void PerformanceNavigation::trace(Visitor* visitor)