macOS text substitutions: More granularity in how HTML attributes change behavior.

With this change, `autocorrect=off` turns off all substitutions, and
`spellcheck=false` just turns off quote and dash substitution, leaving
custom substitutions on.

Bug: 42434
Change-Id: I9ddf49f765e0ce061c8431563768f02e802d919b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1672539
Auto-Submit: Sidney San Martín <sdy@chromium.org>
Reviewed-by: Avi Drissman <avi@chromium.org>
Commit-Queue: Avi Drissman <avi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#671798}
1 file changed