Don't allow hotkeys to activate un-activatable menu items on linux.
Don't allow hotkeys to activate un-activatable menu items on linux.

BUG=9400
Review URL: http://codereview.chromium.org/56184

git-svn-id: dd90618784b6a4b323ea0c23a071cb1c9e6f2ac7@13025 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser