Selenium - Override javascript functions to ignore downloading process

I have got an issue with downloading process on IE 8. This browser blocks my automatic-download functionality on my app so that I could not work with my test case any more after that. In my case, I didn't care about the file is downloaded or not, I just focus on the result after downloading process finished successfully. Therefore, I found a solution to ignore this process so that I can work normally.

I use Primefaces, here is the remote command to trigger the download process

<p:remoteCommand name="cmdGenerateDocument" actionListener="#{logic.onGenerateDocument}" update="xrflDocumentCreationPanel" oncomplete="clickDownloadButton();"/>

The following is my test case:

@Test
 public void shouldUpdateStep6ToWarningIfStep1IsValidAfterFinished(){
  MainPage mainPage = new MainPage();
  waitForLoading(mainPage.getDriver());
  
  EmployeeDetailPage empDetailPage = new EmployeeDetailPage();
  waitForLoading(empDetailPage.getDriver());
  empDetailPage.fillDataForAllFields();
  
  mainPage.clickNext();
  waitForLoading(mainPage.getDriver());
  
  mainPage.clickNext();//move to step 3
  waitForLoading(mainPage.getDriver());
  
  mainPage.clickNext();//move to step 4
  waitForLoading(mainPage.getDriver());
  
  mainPage.clickNext();//move to step 5
  waitForLoading(mainPage.getDriver());
  
  //avoid issue with download automatically on IE8
  mainPage.ignoreDownloadProcess(); 
  
  mainPage.clickNext();//move to step 6
  waitForLoading(mainPage.getDriver());
  
  mainPage.jumpToEmployeeDetailTab();
  waitForLoading(mainPage.getDriver());
  
  empDetailPage.setEmptySalutaion();
  waitForLoading(mainPage.getDriver());
  
  mainPage.jumpToDocumentCreationTab();
  waitForLoading(mainPage.getDriver());
  
  assertTrue(mainPage.isRequriedFinishedAllStepsMessageShown());
  assertTrue(mainPage.isRequriedMessageShownOnStep1());
  assertTrue(mainPage.isStep6Warning());
 }

The content of function "ingnoreDowloadProcess()"

public void ignoreDownloadProcess() {
  String script = "clickDownloadButton = function(){};";
 ((JavascriptExecutor) getDriver()).executeScript(script);
}