Remove beforeload events.

LayoutTests/fast/dom/HTMLScriptElement/dont-load-unknown-type.html

 <div id="console"></div>
 <script>
   if (window.testRunner) {
     testRunner.dumpAsText();
     testRunner.dumpResourceResponseMIMETypes();
   }
 
   function fail(str) {
     var element = document.createElement("p");
     element.innerHTML = str;
     document.getElementById("console").appendChild(element);
   }
 
   var bogus_script = document.createElement("script");
   bogus_script.type = "bogus";
   bogus_script.src = "shouldnotexecute.js";
-  bogus_script.addEventListener("beforeload", function() { fail('beforeload called on dynamic script that won\'t be loaded'); }, false);
   document.getElementsByTagName("head")[0].appendChild(bogus_script);
 </script>
 <script type="fake" src="shouldnotexecute.js"></script>
-<script type="dummy" src="shouldnotexecute.js" onbeforeload="fail('beforeload called on parser inserted script that won\'t be loaded');"></script>
 Unknown script types should not be loaded nor executed. If this test fails, an extra line will appear in the output with the script's MIME type.