Bug 1649840: Adapt wrench to SWGL API changes. r=lsalzman
Bug 1649840: Adapt wrench to SWGL API changes. r=lsalzman

swgl::Context::init_default_framebuffer takes two new arguments, for providing a
frame buffer owned by something else. swgl::Context::get_color_buffer returns an
extra value, describing the stride of the buffer in addition to the width.

Differential Revision: https://phabricator.services.mozilla.com/D81896

[ghsync] From https://hg.mozilla.org/mozilla-central/rev/5f34493d83d344553bcd2bd7879b05082908e5ba

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