GTK: Check return value from gtk_container_get_children().
GTK: Check return value from gtk_container_get_children().

BUG=58981
TEST=Go to webpage that requires translation. Press Translate should not cause a crash.
Review URL: http://codereview.chromium.org/3771001

git-svn-id: dd90618784b6a4b323ea0c23a071cb1c9e6f2ac7@62430 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