Fix multiple-updating-of-numeric-inputs

Summary: Fixes T3257, in which we were inadvertently updating props by not-cloning when we should have. Also removed whitespace and called out some potentially deletable code.

Test Plan: Add multiple numeric inputs and notice that they don't all party-update anymore.

Reviewers: aria

Reviewed By: aria

Maniphest Tasks: T3257

Differential Revision: http://phabricator.khanacademy.org/D13736