Bug 1441308 - Ensure lazy init of debug renderer in draw_frame_debug_items r=gw
Bug 1441308 - Ensure lazy init of debug renderer in draw_frame_debug_items r=gw

Document splitting is crashing with early initialization of the debug
renderer. Not sure why, and this is just a temporary workaround, but
one that I think we want anyway, as we don't want to be unnecessarily
lazy-initting the debug renderer.

Depends on D20698

Differential Revision: https://phabricator.services.mozilla.com/D20700

[wrupdater] From https://hg.mozilla.org/mozilla-central/rev/deb6826900252a703b5211a6dbd29cad21b009e3

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