Replace free isnan with std::isnan

chrome/browser/ui/webui/engagement/site_engagement_ui.cc

Index: chrome/browser/ui/webui/engagement/site_engagement_ui.cc
diff --git a/chrome/browser/ui/webui/engagement/site_engagement_ui.cc b/chrome/browser/ui/webui/engagement/site_engagement_ui.cc
index d53fe7aab36f824aadf4811fbdccf20c0a040281..e14a273c03216ff25425ff1667bf11a869bf4196 100644
--- a/chrome/browser/ui/webui/engagement/site_engagement_ui.cc
+++ b/chrome/browser/ui/webui/engagement/site_engagement_ui.cc
@@ -55,7 +55,7 @@ class SiteEngagementUIHandlerImpl : public SiteEngagementUIHandler {
                                        double score) override {
     GURL origin_gurl(origin.get());
     if (!origin_gurl.is_valid() || score < 0 ||
-        score > SiteEngagementScore::kMaxPoints || isnan(score)) {
+        score > SiteEngagementScore::kMaxPoints || std::isnan(score)) {
       return;
     }