Bug 1662646 - Remove `RendererOptions::max_instance_buffer_size`. r=gw
Bug 1662646 - Remove `RendererOptions::max_instance_buffer_size`. r=gw

It's never set to anything other than the default, so we can hardwire it as a
constant.

Depends on D89102

Differential Revision: https://phabricator.services.mozilla.com/D89103

[ghsync] From https://hg.mozilla.org/mozilla-central/rev/ac00aadf484f1354c0034d53bc44d6dfa3e147cc

servo/webrender,servo/webrender,servo/webrender,servo/webrender,servo/webrender,servo/webrender