Bug 1722838 - Add DisplayListPayload struct r=jrmuizel,gfx-reviewers,nical
Bug 1722838 - Add DisplayListPayload struct r=jrmuizel,gfx-reviewers,nical

Although this currently only contains the existing data u8 vec of
serialized bytes, it will allow us to expand this structure in
future to contain other byte arrays.

This will be used for storing other payload information, such as
interned primitive types or data updates.

Differential Revision: https://phabricator.services.mozilla.com/D121160

[ghsync] From https://hg.mozilla.org/mozilla-central/rev/18d3ab530ed7ffa04ee9978f8ee9779887765f4a

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