为什么env里的pointerEventsSupported属性判断时要加上ua判断？

[DI404N]

开发时遇到一个问题：

上面这段代码（模拟拖拽场景，因为要拖拽的元素很小，所以是给document监听mousemove事件）在Edge浏览器中，mousedown之后，如果不mouseup，mousemove事件不会触发，但是在Chrome中是正常的。在Chrome中e.event的类型是MouseEvent；而Edge中e.event的类型是PointerEvent，然后调用了e.stop取消了事件，导致了mousemove不会再被触发。
问题的根因是，zrender的env的代码中判断pointerEventsSupported要加上ua判断，限制pointerEventsSupported只有在edge和ie可用，为什么要这样写呢？

[plainheart]

应该是历史遗留问题，这个判断逻辑很早就是这样，不过原来有段注释，可供参考：

// (1) Firefox supports pointer but not by default, only MS browsers are reliable on pointer
// events currently. So we dont use that on other browsers unless tested sufficiently.
// For example, in iOS 13 Mobile Chromium 78, if the touching behavior starts page
// scroll, the pointermove event can not be fired any more. That will break some
// features like "pan horizontally to move something and pan vertically to page scroll".
// The horizontal pan probably be interrupted by the casually triggered page scroll.
// (2) Although IE 10 supports pointer event, it use old style and is different from the
// standard. So we exclude that. (IE 10 is hardly used on touch device)

[DI404N]

有修复计划吗？