Bug 1594091 - Move clip_task_address to the second half of the glyph …
…instance y field. r=gw Depends on D51882 Differential Revision: https://phabricator.services.mozilla.com/D51883 [wrupdater] From https://hg.mozilla.org/mozilla-central/rev/c86523dab3c48d8185787f09338b57efeb3f86b0