[Spellcheck] Don't show the confirm bubble (and therefore don't turn on Google suggestions) in this rare case -- linux, non-browser window. Since linux will be updated, this is a quick fix until then.

BUG=302419
TEST=Go to chrome://help, hit "Report an Issue", type something, open the context menu and select "Ask Google for Suggestions". Note that the browser does not crash.

Review URL: https://codereview.chromium.org/27249002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@228589 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 228589