Prevent ThreadableLoaderClient methods from being called after failure notification

Source/core/page/EventSource.cpp

 /*
  * Copyright (C) 2009, 2012 Ericsson AB. All rights reserved.
  * Copyright (C) 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2011, Code Aurora Forum. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1. Redistributions of source code must retain the above copyright
@@ skipping 301 matching lines @@
 
 void EventSource::didFailRedirectCheck()
 {
     abortConnectionAttempt();
 }
 
 void EventSource::abortConnectionAttempt()
 {
     ASSERT(m_state == CONNECTING);
 
-    if (m_requestInFlight) {
-        m_loader->cancel();
-    } else {
-        m_state = CLOSED;
-    }
+    m_loader = nullptr;
+    m_state = CLOSED;
+    networkRequestEnded();
 
-    ASSERT(m_state == CLOSED);
     dispatchEvent(Event::create(EventTypeNames::error));
 }
 
 void EventSource::parseEventStream()
 {
     unsigned bufPos = 0;
     unsigned bufSize = m_receiveBuf.size();
     while (bufPos < bufSize) {
         if (m_discardTrailingNewline) {
             if (m_receiveBuf[bufPos] == '\n')
@@ skipping 110 matching lines @@
     return event.release();
 }
 
 DEFINE_TRACE(EventSource)
 {
     RefCountedGarbageCollectedEventTargetWithInlineData::trace(visitor);
     ActiveDOMObject::trace(visitor);
 }
 
 } // namespace blink