Fixed style errors in src/formats/plain.js

[teresa0605]

Passed lint tests.

[coveralls]

Pull Request Test Coverage Report for Build 4505461191

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 84.971%

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Totals
Change from base Build 4505308263:	0%
Covered Lines:	22589
Relevant Lines:	25344

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💛 - Coveralls