Fix the 'for loop' snippet missing index bug.

In C/C++ file, the 'for' snippet missing the index 'i' after first ';'
![original](https://f.cloud.github.com/assets/956438/2312453/3dfe0346-a2fc-11e3-910f-34d62ac14f87.gif)

After fixed:
![fixed](https://f.cloud.github.com/assets/956438/2312466/66127a88-a2fc-11e3-8380-fc93c1d7b9e7.gif)