text: function isGtk()
  {
      return navigator.userAgent.includes("WebKitTestRunnerGTK");
  }
  
  function isEfl()
  {
      return navigator.userAgent.includes("WebKitTestRunnerEFL");
  }
  
  function videoCanvasPixelComparisonTolerance()
  {
      if (isGtk() || isEfl())
          return 6;
  
      return 2;
  }
  