code: function jscoverage_getViewportHeight() {
  //#JSCOVERAGE_IF /MSIE/.test(navigator.userAgent)
    if (self.innerHeight) {
      // all except Explorer
      return self.innerHeight;
    }
    else if (document.documentElement && document.documentElement.clientHeight) {
      // Explorer 6 Strict Mode
      return document.documentElement.clientHeight;
    }
    else if (document.body) {
      // other Explorers
      return document.body.clientHeight;
    }
    else {
      throw "Couldn't calculate viewport height";
    }
  //#JSCOVERAGE_ENDIF
  }
docs: http://www.quirksmode.org/viewport/compatibility.html