50ca364f39
We recently added experimental support for this element only recently, and it was never enabled by default on release. Our implementation has been preffed-off on all branches for a little while via bug 1954608; and this patch removes the implementation entirely, for reasons discussed in https://bugzilla.mozilla.org/show_bug.cgi?id=1958839#c0 This patch is a squashed backout of the following 6 changesets, listed in reverse chronological order: https://hg.mozilla.org/mozilla-central/rev/efb626444437 https://hg.mozilla.org/mozilla-central/rev/ae8af0edf737 https://hg.mozilla.org/mozilla-central/rev/dd3fac9da2c1 https://hg.mozilla.org/mozilla-central/rev/d5e958d3caae https://hg.mozilla.org/mozilla-central/rev/acdd71cd851b https://hg.mozilla.org/mozilla-central/rev/86f62a648ef0 Fortunately none of the backouts needed manual merge-conflict-resolution, so this is an entirely mechanical backout patch. Differential Revision: https://phabricator.services.mozilla.com/D247668