Do not include comments in the sig AST
Do not include comments in the sig AST

Summary: It turns out that the comments were being stored twice under types-first; once with the normal AST and once with the sig AST. D15472001 transitions to using the comments from the normal AST, and this diff removes comments from the sig AST for the memory savings.

Reviewed By: jbrown215

Differential Revision: D15587096

fbshipit-source-id: 739d56f7b9f83c44d3aadb1fb6ef3d115cd923e8

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