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

third_party/WebKit/Source/core/dom/Document.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2011, 2012 Apple Inc. All
  * rights reserved.
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved.
  * (http://www.torchmobile.com/)
  * Copyright (C) 2008, 2009, 2011, 2012 Google Inc. All rights reserved.
@@ skipping 4575 matching lines @@
       "The provided event type ('" + event_type + "') is invalid.");
   return nullptr;
 }
 
 void Document::AddMutationEventListenerTypeIfEnabled(
     ListenerType listener_type) {
   if (ContextFeatures::MutationEventsEnabled(this))
     AddListenerType(listener_type);
 }
 
-void Document::AddListenerTypeIfNeeded(const AtomicString& event_type) {
+void Document::AddListenerTypeIfNeeded(const AtomicString& event_type,
+                                       EventTarget& event_target) {
   if (event_type == EventTypeNames::DOMSubtreeModified) {
     UseCounter::Count(*this, UseCounter::kDOMSubtreeModifiedEvent);
     AddMutationEventListenerTypeIfEnabled(DOMSUBTREEMODIFIED_LISTENER);
   } else if (event_type == EventTypeNames::DOMNodeInserted) {
     UseCounter::Count(*this, UseCounter::kDOMNodeInsertedEvent);
     AddMutationEventListenerTypeIfEnabled(DOMNODEINSERTED_LISTENER);
   } else if (event_type == EventTypeNames::DOMNodeRemoved) {
     UseCounter::Count(*this, UseCounter::kDOMNodeRemovedEvent);
     AddMutationEventListenerTypeIfEnabled(DOMNODEREMOVED_LISTENER);
   } else if (event_type == EventTypeNames::DOMNodeRemovedFromDocument) {
@@ skipping 16 matching lines @@
     AddListenerType(ANIMATIONITERATION_LISTENER);
     if (View()) {
       // Need to re-evaluate time-to-effect-change for any running animations.
       View()->ScheduleAnimation();
     }
   } else if (event_type == EventTypeNames::webkitTransitionEnd ||
              event_type == EventTypeNames::transitionend) {
     AddListenerType(TRANSITIONEND_LISTENER);
   } else if (event_type == EventTypeNames::scroll) {
     AddListenerType(SCROLL_LISTENER);
+  } else if (event_type == EventTypeNames::load) {
+    if (Node* node = event_target.ToNode()) {
+      if (isHTMLStyleElement(*node)) {
+        AddListenerType(LOAD_LISTENER_AT_CAPTURE_PHASE_OR_AT_STYLE_ELEMENT);
+        return;
+      }
+    }
+    if (event_target.HasCapturingEventListeners(event_type))
+      AddListenerType(LOAD_LISTENER_AT_CAPTURE_PHASE_OR_AT_STYLE_ELEMENT);
   }
 }
 
 HTMLFrameOwnerElement* Document::LocalOwner() const {
   if (!GetFrame())
     return 0;
   // FIXME: This probably breaks the attempts to layout after a load is finished
   // in implicitClose(), and probably tons of other things...
   return GetFrame()->DeprecatedLocalOwner();
 }
@@ skipping 2078 matching lines @@
 }
 
 void showLiveDocumentInstances() {
   WeakDocumentSet& set = liveDocumentSet();
   fprintf(stderr, "There are %u documents currently alive:\n", set.size());
   for (blink::Document* document : set)
     fprintf(stderr, "- Document %p URL: %s\n", document,
             document->Url().GetString().Utf8().data());
 }
 #endif