environment: put gettext stuff into global environment

Rather than defining _() as a local function in every module, put it
into the global environment (along with C_() and ngettext()).

https://bugzilla.gnome.org/show_bug.cgi?id=649203

js/misc/util.js

@@ -7,9 +7,6 @@ const Shell = imports.gi.Shell;
 
 const Main = imports.ui.main;
 
-const Gettext = imports.gettext.domain('gnome-shell');
-const _ = Gettext.gettext;
-
 /* http://daringfireball.net/2010/07/improved_regex_for_matching_urls */
 const _urlRegexp = new RegExp('\\b(([a-z][\\w-]+:(/{1,3}|[a-z0-9%])|www\\d{0,3}[.]|[a-z0-9.\\-]+[.][a-z]{2,4}/)([^\\s()<>]+|\\(([^\\s()<>]+|(\\([^\\s()<>]+\\)))*\\))+(\\(([^\\s()<>]+|(\\([^\\s()<>]+\\)))*\\)|[^\\s`!()\\[\\]{};:\'\\".,<>?«»“”‘’]))', 'gi');