…NGLE configurations r=kvark

Frames captured by the composition recorder on non-ANGLE configurations were
previously written upside down to disk. We now flip them right side up when
mapping them into memory.

Differential Revision: https://phabricator.services.mozilla.com/D40113

[wrupdater] From https://hg.mozilla.org/mozilla-central/rev/dccb73a9ee2b1ae7e890eac4d18769bfa8f2857b