R1:a6c770217dc8

Fixed whitespace options in Differential.

Summary:
Whitespace options could not be selected and the 'ignore_all' was not working.

Test Plan:
Made sure that whitespace is ignored correctly and selected option is handled
correctly.

Reviewed By: jungejason
Reviewers: jungejason
CC: epriestley, jungejason, tuomaspelkonen
Differential Revision: 149