Why polyfill is used when native is supported? (Promise)

[wintercounter]

I'm using babel-polyfill. I always have such stack trace:

(anonymous function)            @   es6.promise.js:119
perform                                 @   es6.promise.js:61
(anonymous function)            @   es6.promise.js:113
module.exports                  @   _invoke.js:5
queue.(anonymous function)  @   _task.js:31
run                                         @   _task.js:19
listener                                    @   _task.js:23

The question is simple. Why? Chrome has support for native Promises (this is a Chrome stack trace).

[zloirock]

Almost all current Promise implementations have many bugs and most of them can't be fixed without completely replacement Promise constructor, you can find many V8 bugs in this tracker. Current feature detection for Promise includes support @@species pattern (the ultimate feature detection for almost all Promise bugs, support @@species should be added in V8 ~ Chrome 51) and unhandled rejection tracking (added in V8 ~ Chrome 49), so native Promise will be used instead of polyfill only in V8 ~ Chrome 51.

[wintercounter]

Thanks for the answer.