Count beforeload separately for isolated worlds

Source/core/dom/Document.cpp

Index: Source/core/dom/Document.cpp
diff --git a/Source/core/dom/Document.cpp b/Source/core/dom/Document.cpp
index 103175f8472fbe80cba9613572614233ef079e78..9c1e12d0c8ee7e534bb9790fc672873e7e18b46c 100644
--- a/Source/core/dom/Document.cpp
+++ b/Source/core/dom/Document.cpp
@@ -3670,7 +3670,11 @@ void Document::addListenerTypeIfNeeded(const AtomicString& eventType)
     } else if (eventType == EventTypeNames::webkitTransitionEnd || eventType == EventTypeNames::transitionend) {
         addListenerType(TRANSITIONEND_LISTENER);
     } else if (eventType == EventTypeNames::beforeload) {
-        UseCounter::count(*this, UseCounter::BeforeLoadEvent);
+        if (m_frame && m_frame->script()->shouldBypassMainWorldContentSecurityPolicy()) {
+            UseCounter::count(*this, UseCounter::BeforeLoadEventInIsolatedWorld);
+        } else {
+            UseCounter::count(*this, UseCounter::BeforeLoadEvent);
+        }
         addListenerType(BEFORELOAD_LISTENER);
     } else if (eventType == EventTypeNames::scroll) {
         addListenerType(SCROLL_LISTENER);