title: ReferenceError: "validate" is not defined. while trying to submit a form with HTMLUnit
body: <p>I want to submit a form to <a href="http://tagmp3.net/" rel="nofollow noreferrer">this</a> site with HTMLUnit but I get the error in title.</p>
  
  <p><strong>Here is my code:</strong></p>
  
  <pre><code>try (final WebClient webClient = new WebClient(BrowserVersion.CHROME, "127.0.0.1", 57703)) {
      //webClient.getOptions().setThrowExceptionOnScriptError(false);
      final HtmlPage page1 = webClient.getPage("http://tagmp3.net/");
      final HtmlDivision div = (HtmlDivision) page1.getElementById("urlForm");
      final DomNodeList&lt;DomElement&gt; forms = page1.getElementsByTagName("form");
      final HtmlForm form = (HtmlForm) forms.get(0);
      final HtmlTextInput textField = form.getInputByName("filepath");
      final HtmlSubmitInput button = form.getInputByName("button");
      textField.setValueAttribute(url);
      final HtmlPage page2 = button.click();
      System.out.println(page2.getBaseURL());
  }
  </code></pre>
  
  <p><strong>And here is the Error I get:</strong></p>
  
  <pre><code>EcmaError: lineNumber=[4] column=[0] lineSource=[&lt;no source&gt;] name=[TypeError] sourceName=[http://code.jquery.com/jquery-3.1.1.min.js] message=[TypeError: Cannot set property "innerHTML" of undefined to "&lt;form&gt;&lt;/form&gt;&lt;form&gt;&lt;/form&gt;" (http://code.jquery.com/jquery-3.1.1.min.js#4)]
  com.gargoylesoftware.htmlunit.ScriptException: TypeError: Cannot set property "innerHTML" of undefined to "&lt;form&gt;&lt;/form&gt;&lt;form&gt;&lt;/form&gt;" (http://code.jquery.com/jquery-3.1.1.min.js#4)
      at com.gargoylesoftware.htmlunit.javascript.JavaScriptEngine$HtmlUnitContextAction.run(JavaScriptEngine.java:894)
      at net.sourceforge.htmlunit.corejs.javascript.Context.call(Context.java:637)
      at net.sourceforge.htmlunit.corejs.javascript.ContextFactory.call(ContextFactory.java:518)      
      blah blah blah....
  </code></pre>
  
  <p>I tried to turn off script error but it didn't work.</p>
  
  <p>By the way I found this in the HTML of the website:</p>
  
  <pre><code>&lt;form onsubmit="return validate(this)" method="post" action="index.php"&gt;
  </code></pre>
  
  <p>How can I get this fixed?</p>