GitLab

Delete obsolete references to spellcheck files and a switch.

The files listed in chrome/common/owners have been moved to
components/spellcheck/common and are covered by an owners
file there.

The spellcheck switch in ChromeSwitches.java is not used
anywhere (in fact the flag has been removed in
crrev.com/2284583002).

BUG=629609

Review-Url: https://codereview.chromium.org/2341653004
Cr-Commit-Position: refs/heads/master@{#419464}