Avoid firing load events on style elements if there is no listeners for that

third_party/WebKit/Source/core/html/HTMLStyleElement.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2003, 2010 Apple Inc. All rights reserved.
  *           (C) 2007 Rob Buis (buis@kde.org)
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
@@ skipping 89 matching lines @@
 const AtomicString& HTMLStyleElement::media() const {
   return getAttribute(mediaAttr);
 }
 
 const AtomicString& HTMLStyleElement::type() const {
   return getAttribute(typeAttr);
 }
 
 void HTMLStyleElement::DispatchPendingEvent(
     std::unique_ptr<IncrementLoadEventDelayCount> count) {
-  DispatchEvent(Event::Create(loaded_sheet_ ? EventTypeNames::load
-                                            : EventTypeNames::error));
-
+  if (loaded_sheet_) {
+    if (GetDocument().HasListenerType(
+            Document::LOAD_LISTENER_AT_CAPTURE_PHASE_OR_AT_STYLE_ELEMENT))
+      DispatchEvent(Event::Create(EventTypeNames::load));
+  } else {
+    DispatchEvent(Event::Create(EventTypeNames::error));
+  }
   // Checks Document's load event synchronously here for performance.
   // This is safe because dispatchPendingEvent() is called asynchronously.
   count->ClearAndCheckLoadEvent();
 }
 
 void HTMLStyleElement::NotifyLoadedSheetAndAllCriticalSubresources(
     LoadedSheetErrorStatus error_status) {
   bool is_load_event = error_status == kNoErrorLoadingSubresource;
   if (fired_load_ && is_load_event)
     return;
@@ skipping 18 matching lines @@
   if (CSSStyleSheet* style_sheet = sheet())
     style_sheet->setDisabled(set_disabled);
 }
 
 DEFINE_TRACE(HTMLStyleElement) {
   StyleElement::Trace(visitor);
   HTMLElement::Trace(visitor);
 }
 
 }  // namespace blink