Set object is not reactive

[ssche]

Version

2.5.16

Reproduction link

https://jsfiddle.net/86us8zxz/2/

Steps to reproduce

Attach a new Set() object to the data attribute of a component and modify it by using the set's methods (add, delete, etc).

What is expected?

Changes in the set would reflect in the rendered HTML, just like they do for arrays.

What is actually happening?

Nothing - the change of the set isn't picked up by Vue, making this property not reactive. This is unusual because mutations of an array works as expected (see link).

Additional notes

https://jsfiddle.net/86us8zxz/3/ shows that the change in the set seems to be detected (unless the reactive system of Vue works different to my understanding) as the view updates when the set is converted to an array.

[posva]

Duplicate of #6774