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/filter.js

@@ -226,10 +226,10 @@ Filter.canonicalize_term = function (opts) {
    narrow in the URL fragment.  There we do use full
    URI encoding to avoid problematic characters. */
 function encodeOperand(operand) {
-    return operand.replace(/%/g,  '%25')
+    return operand.replace(/%/g, '%25')
                   .replace(/\+/g, '%2B')
-                  .replace(/ /g,  '+')
-                  .replace(/"/g,  '%22');
+                  .replace(/ /g, '+')
+                  .replace(/"/g, '%22');
 }
 
 function decodeOperand(encoded, operator) {