Removed One Time Peaks in timeline

I've arbitrarily set the threshold to 10%. Please let me know if you think it should be smaller.

Here are some old and new screenshots for `mask` CSS property:
![image](https://cloud.githubusercontent.com/assets/634478/3554710/7cace1f6-090f-11e4-9d8b-0cde53dd6488.png)
![image](https://cloud.githubusercontent.com/assets/634478/3554704/6c496942-090f-11e4-9b6f-1b53ac9f9ce6.png)

BUG=#126