We have a few instances of code creating temporary Thebes backed gfxContexts if another gfxContext (either passed in or previously stored) is a Thebes backed gfxContext. This code can only be reached if other code creates Thebes backed gfxContexts, and since I've killed all such other code these propagating instances are now dead code.

https://hg.mozilla.org/integration/mozilla-inbound/rev/128dc044d3f7 https://hg.mozilla.org/integration/mozilla-inbound/rev/aadf68ef25b2 https://hg.mozilla.org/integration/mozilla-inbound/rev/3a090599c39e

https://hg.mozilla.org/mozilla-central/rev/128dc044d3f7 https://hg.mozilla.org/mozilla-central/rev/aadf68ef25b2 https://hg.mozilla.org/mozilla-central/rev/3a090599c39e