lint: Ban two spaces after comma in JS code.

We exclude the frontend tests, mostly because the lint rule isn't that
precise, and the test code has some sample user input that's a bit
funny.

static/js/hash_util.js

@@ -8,7 +8,7 @@ var exports = {};
 exports.encodeHashComponent = function (str) {
     return encodeURIComponent(str)
         .replace(/\./g, '%2E')
-        .replace(/%/g,  '.');
+        .replace(/%/g, '.');
 };
 
 exports.encode_operand = function (operator, operand) {