// Добавить подменю "Поиск изображения в ..." в контекстном меню изображений, от 05.09.2015. .............
((contextMenu, viewimage)=> {

  var menu = contextMenu.insertBefore(document.createElement("menu"), viewimage); 
  menu.id = "searchImagIn";
  menu.setAttribute("label", "Поиск похожих изобр. в ...");
  menu.setAttribute("class", "menu-iconic");
  menu.setAttribute("image", "https://www.google.lv/favicon.ico");
  addEventListener("popupshowing", ()=> menu.hidden = viewimage.hidden, true, contextMenu);
  addDestructor(()=> contextMenu.removeChild(menu));
  
  var array = [
        [ 'Google', 'https://www.google.lv/favicon.ico', 'http://www.google.com/searchbyimage?image_url='],
        [ 'Яндекс', 'http://yastatic.net/morda-logo/i/favicon_islands.ico', 'https://yandex.ua/images/search?text=&rpt=imageview&url='],
        [ 'Tineye', 'http://tineye.com/favicon.ico', 'http://www.tineye.com/search/?pluginver=firefox-1.0&url='],
        [ 'Bing', 'https://www.bing.com/s/a/bing_p.ico', 'http://www.bing.com/images/searchbyimage?FORM=IRSBIQ&cbir=sbi&imgurl=']
              ];
  var menuPopup = menu.appendChild(document.createElement("menupopup"));              
  array.forEach((m)=> {
     var mItem = menuPopup.appendChild(document.createElement("menuitem"));
     mItem.setAttribute("label", m[0]);       
     mItem.setAttribute("image", m[1]);
     mItem.setAttribute("class", "menuitem-iconic");
     mItem.finder = m[2];
  });
  
  menuPopup.onclick =e=> {
     var url = e.target.finder + encodeURIComponent(gContextMenu.imageURL);
// в активной или в фоне
//     e.button ? gBrowser.addTab(url) : gBrowser.selectedTab = gBrowser.addTab(url);
      e.button ? gBrowser.addTab(url) : gBrowser.addTab(url);
     setTimeout(()=> contextMenu.hidePopup(), 20);
  };
  
})(document.getElementById("contentAreaContextMenu"), document.getElementById("context-viewimage"));

<SearchPlugin xmlns="http://www.mozilla.org/2006/browser/search/" xmlns:os="http://a9.com/-/spec/opensearch/1.1/">
<os:ShortName>Google Pictures</os:ShortName>
<os:Description>Google Pictures - поиск картинок по тексту</os:Description>
<os:InputEncoding>UTF-8</os:InputEncoding>
<os:Image width="16" height="16">data:image/png;base64,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</os:Image>
<UpdateInterval>1</UpdateInterval>
<SearchForm>https://www.google.com.ru/imghp?hl=ru</SearchForm>
<os:Url type="text/html" method="GET" template="https://www.google.com.ru/search">
  <os:Param name="hl" value="ru"/>
  <os:Param name="site" value="imghp"/>
  <os:Param name="tbm" value="isch"/>
  <os:Param name="source" value="hp"/>
  <os:Param name="q" value="{searchTerms} -pornhub.com -ytimg.com"/>
</os:Url>
</SearchPlugin>