[PR] [parser] Add comments to conditional_cover and logical_cover
[PR] [parser] Add comments to conditional_cover and logical_cover

Summary:
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Pull Request resolved: https://github.com/facebook/flow/pull/7896

Differential Revision: D16149450

Pulled By: mroch

fbshipit-source-id: 0640d6202d2f1a214d4ab15bd300616ae48823e9

gabelevi/flow,mroch/flow,samwgoldman/flow,gabelevi/flow,facebook/flow,facebook/flow,facebook/flow,samwgoldman/flow,samwgoldman/flow,samwgoldman/flow,samwgoldman/flow,gabelevi/flow,mroch/flow,samwgoldman/flow,mroch/flow,gabelevi/flow,gabelevi/flow,mroch/flow,facebook/flow,gabelevi/flow,facebook/flow,mroch/flow,mroch/flow,mroch/flow,facebook/flow,gabelevi/flow,samwgoldman/flow,facebook/flow