Settings WebUI: Handle out of sync spellcheck when there is 1 language

When there is only 1 supported language and spell check is off for that
language, `browser.enable_spellchecking` should be off. Turning
`browser.enable_spellchecking` on should also turn spell check on for
the 1 language.

Bug: 959943
Change-Id: Ic3d717089aa28f302204c62b317cfff5c2fe1731
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1600384
Commit-Queue: John Lee <johntlee@chromium.org>
Reviewed-by: Esmael El-Moslimany <aee@chromium.org>
Cr-Commit-Position: refs/heads/master@{#657863}
2 files changed