[TextServer] Remove excessive Dictionary checks.

[bruvzg]

Remove dictionary equality check to allow reusing variation dictionary without make a copy:

Allows code like this:

var coords = font.variation_opentype # currently works only with .duplicate()
coords["weight"] = 1000
font.variation_opentype = coords

I'm not sure if there's a way to track dictionary element change to do it like:

font.variation_opentype["weight"] = 1000 # won't work

[YuriSizov]

Thanks!