Use double quote for transformed `displayName` and `data-*`

JSX currently transforms everything to double quote except these two. This way, it's at least consistent and will satisfy half of the people who do put a strict quotation linting on their project.

Test: `jest`, check the double quoted transformed `data-bla="something"`.
Merge pull request #1708 from chenglou/displayName

Use double quote for transformed `displayName`