Add properties to include into toJSON()

[loangodard]

Please add propertiesToInclude into toJSON parameters since it is calling toObject which include this param

[SupremeDeity]

saw this yesterday, for some reason toJSON does not have the include array, and its docstring says otherwise. All the other similar methods like toDatalessJSON do have that include array parameter.

[asturur]

I think docs have been updated. TJSON is a delegate from javascript and has its own signature.
Can you point me to the incorrect docs so i can update them?
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/JSON/stringify

There is a customProperties static field now that you can use to carry over things in json automatically

[SupremeDeity]

@asturur for example here the docstring's example:

fabric.js/src/canvas/StaticCanvas.ts

Line 845 in 798ecdb

toJSON() {

[asturur]

yes is definetely wrong. i think only the object one has been correctly corrected