[Resource Timing] Fix potential double free problem

Source/core/fetch/ResourceFetcher.cpp

Index: Source/core/fetch/ResourceFetcher.cpp
diff --git a/Source/core/fetch/ResourceFetcher.cpp b/Source/core/fetch/ResourceFetcher.cpp
index 79663dbd5eec9c04caaa06168820b5dc953d5e82..e19a9294552b9b9277af4339274120aac2aed1b3 100644
--- a/Source/core/fetch/ResourceFetcher.cpp
+++ b/Source/core/fetch/ResourceFetcher.cpp
@@ -947,12 +947,12 @@ void ResourceFetcher::didLoadResource(Resource* resource)
                 initiatorDocument = document()->parentDocument();
             ASSERT(initiatorDocument);
             RefPtr<ResourceTimingInfo> info = it->value;
+            m_resourceTimingInfoMap.remove(it);
             info->setInitialRequest(resource->resourceRequest());
             info->setFinalResponse(resource->response());
             info->setLoadFinishTime(resource->loadFinishTime());
             if (DOMWindow* initiatorWindow = initiatorDocument->domWindow())
                 initiatorWindow->performance()->addResourceTiming(*info, initiatorDocument);
-            m_resourceTimingInfoMap.remove(it);
         }
     }