One widget I forgot to uncenter

Summary:
Not my best commit message.

Uncenter the sequence widgets.

Test Plan:
[test item](http://localhost:9000/article.html#content=%5B%7B%22content%22%3A%22Hi%20I%27m%20a%20particle%21%5Cn%5Cn%5B%5B%E2%98%83%20sequence%201%5D%5D%22%2C%22images%22%3A%7B%22https%3A%2F%2Fka-perseus-graphie.s3.amazonaws.com%2Fda8df81c78b22f5c69d477d8eabfb583968eaf84.png%22%3A%7B%22width%22%3A400%2C%22height%22%3A70%7D%2C%22https%3A%2F%2Fka-perseus-graphie.s3.amazonaws.com%2Fb59fc02ca1aae800977b8793ed22f647a1aa75ee.png%22%3A%7B%22width%22%3A425%2C%22height%22%3A150%7D%7D%2C%22widgets%22%3A%7B%22sequence%201%22%3A%7B%22type%22%3A%22sequence%22%2C%22graded%22%3Atrue%2C%22options%22%3A%7B%22json%22%3A%5B%7B%22content%22%3A%22aasfaefs%5Cn%5Cn%5B%5B%E2%98%83%20input-number%201%5D%5D%22%2C%22images%22%3A%7B%7D%2C%22widgets%22%3A%7B%22input-number%201%22%3A%7B%22type%22%3A%22input-number%22%2C%22graded%22%3Atrue%2C%22options%22%3A%7B%22value%22%3A42%2C%22simplify%22%3A%22required%22%2C%22size%22%3A%22normal%22%2C%22inexact%22%3Afalse%2C%22maxError%22%3A0.1%2C%22answerType%22%3A%22number%22%7D%2C%22version%22%3A%7B%22major%22%3A0%2C%22minor%22%3A0%7D%7D%7D%7D%2C%7B%22content%22%3A%22basdfsef%22%2C%22images%22%3A%7B%7D%2C%22widgets%22%3A%7B%7D%7D%5D%7D%2C%22version%22%3A%7B%22major%22%3A0%2C%22minor%22%3A0%7D%7D%7D%7D%5D)

Auditors: alex