text: import "../core/document";
  import "../core/vendor";
  import "event";
  
  var d3_event_userSelectProperty = d3_vendorSymbol(d3_documentElement.style, "userSelect"),
      d3_event_userSelectSuppress = d3_event_userSelectProperty
        ? function() {
            var style = d3_documentElement.style,
                select = style[d3_event_userSelectProperty];
            style[d3_event_userSelectProperty] = "none";
            return function() { style[d3_event_userSelectProperty] = select; };
          }
        : function(type) {
            var w = d3.select(d3_window).on("selectstart." + type, d3_eventCancel);
            return function() { w.on("selectstart." + type, null); };
          };
  