lint: Ban use of i18n.t in portico js.

tools/lint-all

@@ -282,6 +282,9 @@ def build_custom_checkers(by_lang):
                          'frontend_tests/node_tests',
                          'static/js/debug.js']),
          'description': 'console.log and similar should not be used in webapp'},
+        {'pattern': 'i18n[.]t',
+         'include_only': set(['static/js/portico']),
+         'description': 'i18n.t is not available in portico pages yet'},
         {'pattern': '[.]text\(["\'][a-zA-Z]',
          'description': 'Strings passed to $().text should be wrapped in i18n.t() for internationalization'},
         {'pattern': 'compose_error\(["\']',