eslint: Disable no-use-before-define for functions.

There are lots of function that will be used before they are defined
when we migrate to ES6 from CommonJS, so disable this rule. Functions
are hoisted and processed by webpack so this is fine.

.eslintrc.json

@@ -77,7 +77,7 @@
                 "varsIgnorePattern": "print_elapsed_time|check_duplicate_ids"
             }
         ],
-        "no-use-before-define": "error",
+        "no-use-before-define": ["error", {"functions": false}],
         "no-useless-constructor": "error",
         "no-var": "error",
         "object-shorthand": "error",