[XHR] Call internalAbort() before firing events

If we fire internalAbort() after handleRequestError(), a new request
initiated by the event handler reusing the same XHR instance will be
aborted.

BUG=402855

Review URL: https://codereview.chromium.org/462053002

git-svn-id: svn://svn.chromium.org/blink/trunk@180326 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/Source/core/xml/XMLHttpRequest.cpp

@@ -982,9 +982,11 @@ void XMLHttpRequest::handleNetworkError()
     long long expectedLength = m_response.expectedContentLength();
     long long receivedLength = m_receivedLength;
 
+    if (!internalAbort())
+        return;
+
     handleDidFailGeneric();
     handleRequestError(NetworkError, EventTypeNames::error, receivedLength, expectedLength);
-    internalAbort();
 }
 
 void XMLHttpRequest::handleDidCancel()