Fix: Title translation doesn't match which id is after 744.

Question id is no longer equal to fId which id is after 744. Using 'fid' to find translation instead.

Author: xuzaixian

plugins/leetcode.cn.js

@@ -74,7 +74,7 @@ plugin.getProblems = function(cb) {
       if (e) return cb(e);
 
       problems.forEach(function(problem) {
-        const title = titles[problem.fid];
+        const title = titles[problem.id];
         if (title)
           problem.name = title;
       });